
■*-> 



Copyright^ 



COPYRIGHT DEPOSIT 



Development 



AND 



Electrical Distribution 
of Water Power 



BY 

LAMAR LYNDON 



FIRST EDITION 
FIRST THOUSAND 



NEW YORK : 

JOHN WILEY & SONS 

London : CHAPMAN & HALL, Limited 
1908 



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LIBRARY of CONGRESsj 

Two Oooies Received 

MAB 30 1 908 

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7ft*A A it IW 
CUSS/4 *Xc. NO, 

COPY' A. 



S ..!*■* !!■«■■ ••--•■ 



Copyright, igo8, 

BY 

LAMAR LYNDON 




PRESS OF THE PUBLISHERS PRINTING COMPANY, NEW YORK 



PREFACE. 

It is to be understood that this work is not a text-book on 
electricity, hydraulics, concrete work, nor construction engineering. 
The purpose has been to produce a purely engineering treatise 
in which all the salient facts concerning the hydraulic development 
of power, its conversion into electrical energy, and its transmission 
over long distances, are collated, and their interdependence shown. 

With but few exceptions, no basic principles of electricity are 
set forth nor are the derivations given of the formulae used. 

With the many excellent works on hvdraulics and electricity 
now published, it is needless to reproduce their contents here. 
It is with the relationships between the available power, methods 
of development, the machinery and apparatus employed, and 
the final use to which the energy will be put, that this book is con- 
cerned. It is to be noted that the use of mathematics has been 
studiously avoided and the text may be followed understandingly 
by any one having an elementary knowledge of algebra. 

The descriptions of plants, taken from prominent technical 
periodicals, is believed to be a valuable addition and innovation, 
both in that the principles set forth in the main body of the book 
are here shown in concrete form, practically applied, and that they 
constitute an aggregated expression of the broad ideas held on 
this subject by that portion of the engineering profession ex- 
perienced in this class of work. 

The author has found, in his own practice, that the best way 

to investigate a problem is to discover all that has been done in 

iii 



IV PREFACE 

the same field by engineers of ability, and take this combined knowl- 
edge and experience as the starting point. Such a method, 
however, involves considerable work and loss of time in searching 
through the files of the technical journals. Assembled here, 
after selection from among a large number, it is believed that the 
ease with which these examples may be referred to justifies their 
reprinting and enhances the usefulness of this book. 

The author wishes here to express his appreciation of the 
courtesy extended by the editors of The Electrical World, The 
Electrical Review, The Engineering Record, and The Engineering 
News, who have kindly permitted the use of abstracts of descrip- 
tions of plants from their respective periodicals. 

Lamar Lyndon. 

New York, October, 1907. 



CONTENTS 



Part I 

HYDRAULIC DEVELOPMENT 

CHAPTER 

I. General Conditions, . 
II. Dams, 

III. Canals and Flumes, . 

IV. Design of Hydro-electric Power-houses, 
V. Water- Wheels, 



PAGE 

I 

16 

32 
38 
5i 



Part II 
ELECTRICAL EQUIPMENT 

VI. General Considerations, . 
VII. Alternating-current Dynamos 
VIII. Transformers, 
IX. Transmission Conductors, . 
X. Pole Line and Accessories, 
XL Lightning Protection, 
XII. Switching and Controlling Apparatus, 



7i 
76 

92 

100 

120 

i35 
141 



APPENDIX 

Computation of Pressures set up in Water Pipes . 152 

v 



J 



y i CONTENTS 



Part III 

DESCRIPTIONS OF HYDRO-ELECTRIC GENERATING 
AND TRANSMISSION PLANTS 

PAGE 

i. Tofwehult- Wester wik Plant in Sweden, . . . 157 

2. Hydraulic Development at West Buxton, Me., . . 164 

Hydraulic Power Development of the Animas Power 
and Water Co. at Durango, Cal. . . . .176 

4. Hydro-electric Plant or the City of Drammen, Norway, 183 

5. Great Falls Station of the Southern Power Co. in 

N. Carolina ..... .... 193 

6. The Hydro-electric Development at Trenton Falls, 

N.Y., .' . . . 208 

7. Hydro-electric Plant of the McCall Ferry Power Co., Pa., 215 

8. The Taylor's Falls-Minneapolis Transmission System, 

Minnesota, . 229 

9. The Kern River Plant of the Edison Electric Co., 

California . . . . . . . . . 263 



DEVELOPMENT AND ELECTRICAL DISTRI 
BUTION OF WATER POWER 



PART I. 

Chapter I. 

GENERAL CONDITIONS. 

The most important factor in the development of a water 
power is to determine, in advance, the actual amount of power 
that may be obtained continuously over a long period of years. 
Failure to give this matter the attention and careful investigation 
which its importance deserves has resulted in financial disaster 
in many instances. Too often, engineers survey hydraulic prop- 
erties, and report that the flow of water is a given quantity per 
second, and therefore the power obtainable is a certain amount. 
Such computations are correct for the particular day on which the 
survey is made, but obviously the amount of water flowing, and, 
therefore, the power, may change within a few hours. Laymen 
who know nothing of engineering are familiar with the variation 
in the flow of streams with the time of the year, and in some years 
the flow is less or greater for a certain season than it normally 
is at the same period. 

At times, water-power development is undertaken on the basis 
of the ability to supply a given amount of power for the greater 
part of the year, and a less amount during the short time of the 
dryest season or when the stream is so greatly flooded that opera- 
tion of water wheels is impossible. This also is an erroneous 
basis on which to determine the value of a water power unless there 
is some class of industry to which the power may be sold, which 



2 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

can use intermittent power and which can suffer stoppage or re- 
duction of its operations without material loss. In this case, if 
the amount of power to be taken by the intermittent power- users 
be previously known, together with the frequency and duration 
of the shut-downs they can allow, a fairly accurate conclusion as 
to the value of the power and the advisability of developing it may 
be formed. 

Still other developments are made having auxiliary steam 
plants, which are used to help out the water power when the stream 
flow is too low to furnish the required energy. This is an ad- 
mirable arrangement, where the value of the power*" sold, during 
the several months when water in plenty is available, is sufficient 
to pay the cost of operating with the assistance of steam, during 
the short time of low water. Usually, however, the proper basis 
on which to fix the amount of available power is to take a series 
of records of stream flow during the times of maximum and 
minimum flow. These observations, to be reliable, should ex- 
tend over several years, or over one year which is admittedly 
the dryest known in a number of years. 

In the United States, the Government haSxOng maintained gauges 
at different points on most of the large rivers, and their records 
are available and may be used in computing the available power 
without making any additional observations on the stream itself. 
In many countries, however, the engineer is dependent on his own 
observations, and as these cannot be carried over a long number 
of years he must fall back on the methods of computation from 
the rainfall, the drainage of the stream, the local conditions as to 
character of the country, its vegetable growths, and whether its 
geological formation is such that underground storage reservoirs 
exist which supply springs that continue to feed the streams dur- 
ing dry weather. With these data, reinforced by experience, a 
fairly accurate determination of the minimum stream flow may 
be arrived at. 

The character of the underbrush, shrubbery and trees, their 
extent; the proportion of wooded area to that denuded of trees, 



GENERAL CONDITIONS 3 

the proportion under cultivation, all have a marked influence on 
the variation in the flow. Trees and shrubs tend to hold the 
rain water and make it move slowly toward the stream — so slowly 
that much of it is absorbed into the earth and then reaches the 
river or its tributary creeks only by percolation which greatly 
retards its movement. These effects combine to equalize the 
amount of water which is given to the stream by each rainfall. 
Rains come intermittently and are of varying volume. The flow 
of streams would be equally intermittent and variable as to volume 
if it were not for these retarding influences. Cases are on record 
where water powers, which were at one time good and satisfactory, 
have been injured by subsequent cutting away of timber and 
underbrush over the drainage area of the streams supplying them. 
These power-plants are now subjected to heavy floods in the wet 
season of the year, and the available water in the dry season is 
smaller than it formerly was. Therefore, this factor must be given 
due consideration. Where springs are numerous, they tend to 
keep the stream flow up in dry weather and these are valuable 
when they discharge enough water to be of real assistance. 

The character of the industries to which the power will be 
transmitted also has to be considered. If the general use is for 
lighting, for driving cotton mills, factories, and the like, the only 
power that can be counted on in the development is that produced 
by the smallest -flow of water that occurs during the entire year. 
Obviously, if an amount of power, greater than this minimum 
flow will furnish, be sold to users, a time will come when some or 
all of them will have to reduce their working capacity, and this 
result tends to prevent consumers making satisfactory contracts 
for power with the development company. 

The minimum flow sometimes may be increased by means 
of storage. When a dam is built across a stream and a lake of 
considerable area is formed, the water thus accumulated may be 
partially drawn off during the dry season, the total water passed 
through the turbines being that furnished by the stream plus that 
of drainage from the lake. In some cases, when the power is 



4 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

used only ten hours per day and the storage area is sufficiently 
great, the water which flows during the night is accumulated in 
the lake, and on the following day the water available for power 
is that supplied by the stream flow plus that impounded during 
the previous night. In this way, the power furnished by a given 
stream may be nearly doubled. 

For the purpose of forming extensive storage lakes, dams 
of great height and length are often constructed, where a small 
dam, further up the stream, and a canal or flume leading to the 
foot of the falls, costing much less, would serve just as well, if 
the question of storage were not involved. 

In order to determine the value of a water power and whether 
or not the investment of its cost of development is warranted, 
the following data must be obtained: 

(i) Variation in quantity of stream flow. 

(2) Amount of power (gross) available at minimum flow. 

(3) Cost of hydraulic development {i.e., dam, canal, tail 
race, forebay, head-gates, flumes, overflowed land, riparian rights). 

(4) Cost of power station and foundations. 

(5) Cost of generating equipment {i.e., water-wheels, gov- 
ernors, generators switchboard, transformers, miscellaneous 
equipment). 

(6) Cost of transmission line (i.e., wire; insulators, poles; 
cross-arms; braces, lag screws). 

(7) Labor, freight, and cost of erection on all work as above. 

(8) Cost of operation per annum. 

(9) Price at which power may be easily sold in the localities 
reached by the transmission lines. 

(10) Annual profit. 

The annual profit as thus computed shows whether the interest 
on the cost is sufficient to make the investment a good one. 

It is, of course, assumed that there is a market for the power, 
or that the conditions justify the belief that cheap power will build 
up a locality and bring power users within the radius of distribu- 
tion of the projected plant. 



GENERAL CONDITIONS 5 

The quantity of stream flow and its variation are arrived at in 
one of the following ways: 

(a) From observations extending over a number of years. 

(b) From records of rainfall and drainage area of stream 
down to location of power house. 

(c) From a few observations made at the time of known low 
water. 

Where possible, all of these means should be used to check 
the final result. 

From (a) and (b) the maximum as well as the minimum flows 
are obtained, and either is, therefore, preferable to (c) alone. 
Neither (b) nor (c) alone should ever be accepted as final, but 
the two always used together to check each other. 

The maximum flow must be known, so that the dam may be 
designed to withstand it, and the spillway — that is, the crest of 
the dam over which the water flows — made long enough to allow 
the maximum volume of water to pass over it without an excessive 
rise in the height of the water over the dam. 

Abnormal increase in the height of water above the spillway 
endangers the dam and may result in its being swept away. 

To determine the flow where no data are available, it is cus- 
tomary to proceed as follows: 

Select two points along the stream about three hundred feet apart. 
These should be located somewhere along the stream where it runs 
straight without curves, bends, falls, or eddy whirls, and the cur- 
rent is down the middle of the stream — not near either bank. 
Make a cross-section survey of the stream at both points, and 
determine the area of each section in square feet. Take the 
average of these two sections — that is, add the areas of the two 
sections together and divide their sum by 2. This gives the mean 
section. At times of high and of low water, take the velocity 
of the stream by means of a float which sinks deeply into the 
water. The float is put into the current of the stream about four 
hundred feet above the upper reference point, so that by the time 
it has been carried down to this point it has attained the velocity 



6 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

of the stream. Observe accurately the time required for the 
float to travel from the upper point to the lower one. Knowing 
the time in seconds and the number of feet the two points are 
apart, the velocity of the stream flow, at the times these obser- 
vations are taken, may be computed. 

The average velocity of the stream is, however, less than that 
of the main stream current, and it is customary to assume the 
average rate of flow as 80 per cent of that of the float. 

The number of cubic feet per second is then computed by 
multiplying the average cross-section of the stream by the average 
rate of flow. 

To make a survey of the cross- sections of the stream it is usual 
to select a time of low water and by means of a surveyor's level 
take the differences in level from the surface of the water out to 
either side of the stream to such a distance that the maximum 
high-water point is reached, care being taken to move outward 
from the stream at right angles to its direction of flow. Obser- 
vations are made at intervals of from two to twenty feet, depending 
on the variation in the contour of the banks, and the distance from 
the water surface out to the maximum high-water level. 

The cross-section of the stream itself is then determined. The 
best way to do this is to stretch a strong iron wire, about -g 3 ^ of 
an inch in diameter, across the stream, this wire having been pre- 
viously marked by small metal or wooden tags spaced along it at 
equal intervals. The distance apart of the tags should be not 
more than ten per cent, of the width of the stream. With a steel 
tape, weighted at one end by a heavy plumb bob, measure the 
depth of the water at each marking on the transversely stretched 
wire, using a small row-boat when necessary. From these data 
the cross- section may be mapped and computed. 

This is done by assuming some scale on the paper, say -^ °f 
an inch, as equal to one foot of horizontal distance, and some other 
greater scale, say one inch, as equal to one foot of vertical measure- 
ment. 

Computing the area of the cross-section of the water may 



GENERAL CONDITIONS J 

be done by any method of integrating irregular surfaces. A simple 
approximate way is to add together all the observed depths and 
divide this result by the number of observations. This gives 
the average depth. Multiply this average depth by the width of 
the stream, in feet, and the product will equal the cross-section 
of the stream in square feet. 

The float should be made of a piece of wood about three feet 
long and from six to ten inches in diameter. Weights should be 




Fig. i. 



fastened to one end of the piece so that it will float vertically, 
with one end submerged and the other projecting only an inch 
or two above the surface of the water. 

In order to observe from the bank the position of the float, 



8 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

it is usual to fasten a small piece of red cloth to a rod or piece 
of wire and drive this rod into the upper end of the float. 

The distance apart of the two points selected to observe the 
float velocity should be accurately measured and stakes driven 
in the ground near the water's edge, to fix these reference points. 

The foregoing instructions are for determining the flow of 
moderate and large- sized streams. 

In measuring small streams it is more accurate and convenient 
to construct a weir dam such as is shown in Fig. i. This is made 
of boards as is indicated, with a notch B extending across about 
two-thirds the width of the stream and deep enough to easily pass 
all the water through it. The edges of the notch must be sharply 
bevelled as shown, the bevelling being on the down-stream side. 

Ten feet up the stream from the weir dam a stake E, having 
a smooth upper surface, should be driven. The upper face of 
this stake must be exactly at the same level as the lower edge of 
the notch B. On this stake the depth of the water above the 
edge of the notch must be measured. Never measure this depth 
at the notch. 

The formula for determining the cubic feet per second of flow is : 

Q = 3-33 X (b — 0.2J1) h f in which 

Q = cubic feet per second, 

b = length of the notch measured in feet, 

h= depth of water over notch measured in feet. 

In order to obviate the necessity of making computations 
from this formula, the following table is given, which shows the 
cubic feet per minute with various depths of water in inches over 
the notch for each inch length of notch up to depths of 24J inches. 

Column No. 1 is the depth in inches over the notch. 

Column No. 2 is the flow in cubic feet per minute corresponding 
to the depth as given in column 1 for each inch length of the notch. 

Thus, for a depth of 10 inches the flow is 12.71 cubic feet 
per minute for each inch length of notch. Therefore a notch 
40 inches wide with 10 inches depth of water over it will pass 
40 X 12.71— 508.4 cubic feet per minute. 



GENERAL CONDITIONS 9 

Table No. i. — Weir Table — Flow for Each Inch in Width. 



Inches 
Depth. 




y* 


%■ 


H 


y 2 


H 

•83 


% 


% 


Inches. 


1 


.40 


•47 


•55 


•65 


•74 


•93 


1.03 


1 


2 


1. 14 


1.24 


1.36 


1.47 


i-59 


1. 71 


1.83 


1.96 


2 


3 


2.09 


2.23 


2.36 


2.50 


2.63 


2.78 


2.92 


3-o7 


3 


4 


3.22 


3-37 


3-5 2 


3.68 


3-83 


3-99 


4.16 


4-3 2 


4 


5 ' 


4-5° 


4.67 


4.84 


5.01 


5.18 


5-36 


5-54 


5-7 2 


5 


6 


5-9o 


6.09 


6.28 


6.47 


6.65 


6.85 


7-o5 


7- 2 5 


6 


7 


7-44 


7.64 


7.84 


8.05 


8.25 


8.44 


8.66 


8.86 


7 


8 


9.10 


9-3i 


9-5 2 


9-74 


9.96 


10.18 


10.40 


10.62 


8 


9 


10.86 


11.08 


11.31 


n-54 


11.77 


12.00 


12.23 


12.47 


9 


10 


12.71 


13-95 


i3- J 9 


13-43 


13-67 


13-93 


14.16 


14.42 


10 


11 


14.67 


14.92 


15.18 


15-43 


15-67 


15.96 


16.20 


16.46 


11 


12 


16.73 


16.99 


17.26 


i7-5 2 


17.78 


18.05 


18.32 


18.58 


12 


n 


18.87 


19.14 


19.42 


19.69 


19.97 


20.24 


20.52 


20.80 


J 3 


14 


21.09 


21.37 


21.65 


21.94 


22.22 


22.51 


22.79 


23.08 


14 


J 5 


23-3 8 


23.67 


2 3-97 


24.26 


24.56 


24.86 


25.16 


25.46 


15 


16 


25.76 


26.06 


26.36 


26.66 


26.97 


27.27 


27.58 


27.89 


16 


17 


28.20 


28.51 


28.82 


29.14 


2 9-45 


29.76 


30.08 


3°-39 


17 


18 


30.70 


31.02 


3*-34 


31.66 


31.98 


3 2 -3* 


3 2 - 6 3 


32.96 


18 


J 9 


33- 2 9 


33-6i 


33-94 


34-27 


34.60 


34-94 


35- 2 7 


35-6o 


19 


20 


35-94 


36.27 


36.60 


3 6 -94 


37.28 


37.62 


37-96 


38.31 


20 


21 


38.65 


39.00 


39-34 


39-69 


40.04 


40.39 


40.73 


41.09 


21 


22 


41-43 


41.78 


42.13 


42.49 


42.84 


43.20 


43-56 


43-9 2 


22 


2 3 


44.28 


44.64 


45.00 


45-38 


45-7 1 


46.08 


46.43 


46.81 


2 3 


24 


47.18 


47-55 


47.91 


48.28 


48.65 


49.02 


49-39 


49.76 


24 



If the depth of water over the notch is not an exact number 
of inches, column 3, 4, 5, 6, 7, 8, or 9 must be used. If the depth 
were iof inches, the flow is given in column 8, and on the same 
horizontal line as the figure 10 in column 1; in this case the flow 
is 14. 16 cubic feet per minute per inch length of notch. Similarly, 
the flow per inch width of notch may be found by taking the number 
out of the table from the column headed by the fraction of an inch, 
and opposite to the even number of inches shown by the depth 
measurement. Multiply the figure so taken by the width of the 
notch in feet, and the result is the cubic feet per minute. To re- 
duce to cubic feet per second, divide the feet per minute by 60. 
Thus, 508 . 4 cubic feet per minute is equal to a flow of 8 . 47 cubic 
feet per second. 

By making numerous observations at different seasons, suf- 
ficient records are finally obtained to settle, fairly well, the variation 



IO DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

in stream flow. This will afterward be modified by the available 
storage, which cannot be computed until the height of the fall is 
determined. 

The fall is found by starting at the head of the shoals with an 
engineer's level, the lower end of the level rod being against the 
surface of the water for the first observation. The second obser- 
vation is made with the level rod on the bank and succeeding 
observations are made with the level rod on the ground, working 
down to the foot of the shoals. When this point is reached the 
last observation is taken with the end of the rod against the surface 
of the water, and thus the difference in level between the head and 
foot of the shoals is determined. 

Generally, the rod should be moved over to the water at inter- 
vals so that the drop at various points may be taken as well as the 
total difference in head. Where the whole drop is in one precipi- 
tous fall, only the difference in level between the top and bottom 
of the fall is obtainable or necessary. 

After measuring the fall, the calculation of gross available 
power is very simple. A horse-power (gross) is produced when 
8.8 cubic feet per second flows and falls a distance of one foot, 
or if one cubic foot per second falls a distance of 8 . 8 feet. There- 
fore, to find the power of a given fall, multiply the cubic feet flow 
per second by the fall in feet and divide the product thus obtained 
by 8.8. The result will be the gross horse-power of the fall. 
For instance, take a fall of 35 feet and a flow of 26 cubic feet per 
second: 35 X 26 = 210. 210 -f- 8.8 = 103. 4 = gross H.P. 

Where metric measurements are used these figures are changed 
as follows: one cubic metre of water per second falling through 
one metre will yield 13.2 H.P. gross. 

For example, take 6 cubic metres of water per second falling 
through 12 metres. The product of 6 by 12 = 72. Multiplying 
this by 13.2 the result gives 950 H.P. 

These amounts, however, do not represent the power that 
may be actually utilized. In every machine or motor there is 
some loss. The loss in the best forms of water wheels is about 



GENERAL CONDITIONS II 

20 per cent, of the gross; so that the net power available at the 
turbine shaft is 80 per cent, of the gross. Thus, if the calculated 
gross-power is 100 horse-power, the amount that may be obtained 
at the turbine shaft is 80 H.P. Having determined the power ob- 
tainable at the turbine shaft at times of lowest water, if this is ample 
for all possible needs, the development may be made in the most 
inexpensive manner practicable for the particular conditions. If, 
however, the power is insufficient when the water is low, it becomes 
necessary to consider the question of storage. 

In computing the available volume of water for storage, it 
must be remembered that the level of the reservoir can only be 
lowered a comparatively small amount. If the storage lake be 
drawn off too much and its level sinks too far, the head acting on 
the water-wheels will be diminished by an amount that will impair 
the operation of the plant. The drop in level of the reservoir should 
never exceed thirty per cent, of the effective head. In cases of ex- 
treme necessity this drop may be exceeded, but all calculations as to 
the amount of power obtainable from a given stream with storage 
should be based on a drop in head not exceeding thirty per cent. 

The amount of storage is more often regulated by financial 
considerations than engineering possibilities. A concrete ex- 
ample will render the subject clear. 

Consider a stream 220 feet wide having a fall of 50 feet in a 
distance of 3 miles. There are three methods of development 
possible. One is to cut a canal from the head of the shoals to 
the foot, this canal running level along the hillsides, and construct 
a small deflecting dam at the head of the shoals. The second is 
to build a dam at some point between the head and foot of the 
shoals, and run a canal the remaining distance to the foot of the 
shoals. The third method would be to build a large dam at the 
foot of the shoals and dispense with the canal. 

Assume that the length of the three dams would be the same. 
Then their cost would be approximately as follows — assuming 
that the base of each dam is at an average depth of 10 feet below 
surface of the water: 



12 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

First dam to be 4 feet above water surface, making a total 
height of 14 feet. 

Second dam to be placed half-way down the shoals and to be 26 
feet above the surface of the water, making the total height =36 
feet. 

Third dam to be placed at the foot of the shoals and to be 5 1 feet 
above the surface of the water, making a total height of 61 feet. 

The costs are: first dam, $5,500; second dam, $35,000; and 
third, $90,000. 

The cost of canal to carry 300 cu. ft. per second will be about 
$10,000 per mile if cut through ordinary clay and no blasting 
is necessary. Adding the cost of canal cutting to that of the dam 
for each development, the total costs are — 

1st development $35,000 (dam $5,000 + 3 miles of canal at 
$10,000); 

2d development $50,000 (dam $35,000 + ij miles canal at 
$10,000); 

3d development $90,000. 

Assume the selling value of the power to be $15 per annum 
for 10-hour power; the minimum flow is 160 cubic feet per second, 
and this minimum flow lasts for 28 days in extreme dry sea- 
sons. The power desired is that furnished by 300 cubic feet per 
second. 

With the first development at the lowest cost there is no storage 
capacity. In the second, the lake formed will be ij miles long 
and will have an average width of possibly 350 feet. This latter 
is determined by contours which are run at the time of surveying 
the water power, and the figure here taken is only an assumption. 

The area of this lake is 1.5 X 5,280 X 350 = 2,772,000 sq. ft. 
The depth down to which the lake may be drawn is 10 feet in 
this case (20 per cent, of the head). The total water available for 
storage is, therefore, 2,772,000 X 10 = 27,720,000 cu. ft. 

If the amount is drawn off in 28 days the draft per day is 
990,000 cubic feet and for 10-hour power the draft per second is 
27.5 cubic feet. At an average head of 45 feet and 80 per cent. 



GENERAL CONDITIONS 1 3 

efficiency the additional power obtained from storage during 

. 27.5 X 45 X .80 

the drv season is —112 H.P., and its additional 

8.8 

cost is $15,000. 

This is over $133 per horse-power, which is a high figure for 
the hydraulic power only and not to be considered in localities 
where the yearly rental is not above $15 per horse-power. 

Consider now the third possible development. The lake 
formed by its dam would be 3 miles long and (assumedly) average 
450 feet wide. The volume of storage, with 10 feet depth of draft, 
would be 10 X 3 X 5,280 X 450=71,180,000. The draft per 
second, if 28 days be allowed for the total storage discharge, is 70.6 
cubic feet, which at an average head of 45 feet equals 300 horse- 
power additional, derived from storage. Its additional cost is 
$90,000 — $3 5,000 = $5 5,000, or $183.00 per horse-power, which 
is an excessive cost. Therefore in this case it would be best, from 
a financial standpoint, to develop with the small dam and long canal. 
Certain conditions might alter this conclusion. If, for instance, 
the stream flows through flat country, and the lake, formed by the 
lower dam, were extremely wide, so that the amount of storage 
would be greatly in excess of the above figures, the cost per horse- 
power would be correspondingly reduced, and one of the higher 
cost developments would be the advisable one. Also, if the ex- 
treme low water during the dry season should last only 14 days, 
the draft per second, and the resulting power, would be increased 
in the ratio of 28 to 14. This would reduce the cost per horse-power 
from $133 to $66.50 in the first instance, and from $183 to $91.50 
in the second, both of which figures are admissible. Obviously 
these questions can be settled only by having a complete survey 
made of the property, and a number of reliable observations of 
the stream flow obtained. 

The question of carrying part of the load during low water 
by means of an auxiliary steam plant is also a subject for considera- 
tion in every prospective hydro- electric development. 

Taking the conditions as given in the foregoing example, there 



14 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

are 28 days in which a storage equal to 120 cu. ft. per second is 
required to make the normal power due to 300 cu. ft. per second 
continuous. At 50 feet head and 80 per cent, efficiency this cor- 
responds to 545 H.P. This may be obtained by a steam plant 
costing approximately $18,000, if the plant be of a simple charac- 
ter. The cost of operating such a plant would be about $8 per 
diem for extra labor and about $28 per diem for fuel and 
extras, or a total of $36 per day. The cost of supplying this 
power for 28 days would therefore be $1,008, which represents 
a capitalization of $12,600 taken at 8 per cent. The equivalent 
cost then of a steam-assisted hydraulic plant, referred to water 
power only, as a basis, and considering the first development be- 
fore discussed, is $3 5,000 + $18,000 + $12,600 = $65,600. Obviously 
this is the plant best adapted to the conditions since it is cheaper 
than development No. 3, costs but little more than development 
No. 2, and gives the full power of the plant the year round, which 
neither of the others will do. 

The steam auxiliary allows a much larger development of 
a given water power than is usually obtainable in any other way. 
If the stream, before discussed as an example, supplied 500 
cu. ft. per second at all times except about 40 days in the year, 
400 cu. ft. except 30 days, 300 cu. ft. except 14 days, and 160 
cu. ft. as a minimum, the power obtainable could be based on 
500 cu. ft. per second, and with a proper-sized auxiliary steam 

500 X 50 X .80 per cent 

plant, would be =2,275 H.P. as agamst 

8.8 

1,362 H.P. when 300 cu. ft. per second are used. The steam 

plant must be large enough to furnish the power represented by 

the difference between 500 and 160 cu. ft. per second or 380 

cu. ft. This, at 50 foot head, equals 1,738 H.P. The cost of 

the steam plant will be about $60,000. 

It will be called on to furnish power as follows: 1,738 H.P. for 

14 days. Power due to 200 cu. ft. of water per second =(500 — 

300) for 16 days. This amounts to 910 H.P. Power due to 100 

cu. ft. of water per second (500 — 400) for 10 days = 455 H.P. 



GENERAL CONDITIONS 1 5 

The H.P.-days' total are: (1,738 X 14) = 24,300 

910 X 16 =14,55° 
455 X 10 = 4,550 

Total 43,400 H.P. days. 

Taking the cost of fuel, oil, waste, etc., at 6 cents per H.P. -day 
and extra labor at $8 per day, the annual cost of operating the 
steam plant will be: 

40 days' labor at $8 $320.00 

43,000 H P.-days at 6 cts 2,604.00 

$2,924.00 

Depreciation on steam plant at 2* 

per cent, on $60,000 1,200.00 

Total cost of operation $4,124.00 

which is interest at 8 per cent, on a capitalization of about $52,000. 

Adding together the actual cost together with the equivalent 
capitalization, the cost of the plant to obtain 1,700 H.P. additional 
is $112,000. This is $66 per H.P., which is a low cost and would 
warrant this character of development. 

Of course, with change in any of the .ocal conditions, these 
figures would undergo variation which might be so considerable 
as to change the result completely and make some other course 
advisable. The foregoing is all given simply to indicate the fac- 
tors involved in determining the proper form of development 
and to show how engineers proceed in arriving at their conclu- 
sions. The main object always to be kept in mind is the produc- 
tion of the most dividends and making the development at the 
lowest possible cost. 

* Taken at this figure because of the short period of plant operation during the 
year. 



CHAPTER II. 

Dams. 

Before discussing the various types of dams and their relative 
merits it is necessary to investigate the forces acting to rupture or 
overturn them. 

In determining the stability of dams it is essential to find the 
centre of gravity of the section. Following are a few simple rules. 

For a section like Fig. 2 or any quadrilateral having two paral- 
lel sides, bisect the parallel sides and join the bisections with a 
line Thus bisect A B at Z and C D at W and join these points 
by the line Z W. Extend each of the parallel sides, one in one 



A Z 




A \ \ , 




\ V 


/ 




s 




/ 




s 




s 




s 




s 


\ \ 


s 




s 


1 ^ \ 


s 


\ \ 


s 




/ 


1 \ ' 




\ f 


\s 


\ s 




\ ' 




1 \ ' 




>G 






' \ 




1 ' . 




s \ 




\ 




Y \ 




/\ \ 






\ 






S 1 \ 




1 \ 





X C vV D 

Fig. 2. 

direction, the other in the opposite direction, the amount of the 
extension of each side being equal to the length of the opposite 
side. Join the ends of these extensions by a line. The intersec- 
tion of this line with the line joining the bisected sides is the centre 
of gravity. Thus, A B is extended to the right an amount equal 
to C D, while C D is extended toward the left by an amount equal 

16 



DAMS 



17 



to A B. The line Y X joining the ends of these extensions 
intersects line Z W at G, which point is the centre of gravity. 

The centre of gravity of a triangle is on the line joining the up- 
per angle with the middle point of the base and is one-third the 



h 


A 


// / 




, 


I 


7 i G \ 


/ ' /G / 




1 


r 


/ 1 \ 


/ / / 





Fig. 3. 

altitude of the triangle upward from the base. Fig. 3 indicates 
the location of the centre of gravity of triangular sections. 

The centre of gravity of a figure like that shown in Fig. 4 may 
be obtained by dividing it into two parts such as A B E K and find- 




Fig. 4. 

ing its centre of gravity as at g and C K D and finding its, as at 
£'. The centre of gravity of the figure is on the line joining these 
2 



i8 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



two separate centres. Then re-divide the figure into two other 
forms such as A B F C and F C E D. Take their respective 
centres of gravity at g" and g"' and join them by a line. The inter- 
section G of the two lines joining the two sets of cen- 
tres of gravity is the centre of gravity of the figure. 

For contours like Fig. 5, it is sufficiently accurate to 

assume them to be as shown in the dotted lines, giving 

a quadrilateral with two parallel sides 

on a rectangle. The centre of gravity is 

easily found as above. 

In Fig. 6 is indicated in outline the 
section through a dam with the water 
backed up behind it. 
Consider one foot of length of the dam. The pressure of the 
water against the dam at the bottom is equal to the weight of one 




Fig. 5. 




Fig. 6. 



cubic foot of water multiplied by the depth in feet; i.e., \ih = the 
depth in feet, the water pressure at the bottom of the dam, per foot 
length of dam, is 62.5 X h. To make this clear refer to Fig. 7. 



DAMS 



l 9 



Consider a dam with a depth of water behind it of 10 ft. Take 
a prism of water one foot wide measured along the length of the 
dam and one foot long measured back from the dam. This prism 
contains 10 cubic feet of water weighing 62.5 X 10 or 625 lbs. 




■m^^^ 



Fig. 7. 



Its area of support at the bottom is one square foot. Therefore 
the pressure at the bottom is 625 lbs. per square foot, which is 
the same as 62 . 5 X h, when h = depth of water in feet. The depth 
of water at the top being zero, the pressure at the top is likewise 
zero. The average pressure per square foot of surface against 
the dam, tending to push it out of position, is the average of the 
top and bottom pressures, which is one-half the sum of the two. 
o + W h ■*• 2 = J W h, is therefore the average pressure per square 
foot against the dam, W being the weight of a cubic foot of water. 
The total pressure from top to bottom of the dam (per foot 
of horizontal length) is obviously equal to the average pressure 
per square foot multiplied by the height in feet; or is equal to 

W h 2 

. The dam must therefore be amply strong for 



%WhXh 



62.5 h 2 
each foot length to resist the pressure equal to or, in metric 



20 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

measurements, the pressure per metre length of the dam is 480 h 2 
kilos when h = depth in metres. This covers only the effect of the 
tendency of the water to push the dam down stream. As a matter 
of fact dams most often fail by overturning. 

The forces involved here are not difficult to understand and 
may be easily understood by referring to Fig. 6. 

The diagonal line O A is the indicator of the horizontal press- 
ure against the face of the dam at any depth of water. Thus, 
if the diagram be drawn to some convenient scale, so that the 
depth h is equal to the number of feet depth of water and the 
distance B A is equal to 62 . 5 X h to the same or any other con- 
venient scale, then the horizontal distance from the face line of 
the dam O B to the diagonal O A at any vertical point will be equal 
to the horizontal pressure against the surface of the dam at that 
depth. Thus p 1 , p?, p 3 , p^ are the different pressures at the various 
depths taken. Mathematically, the area of the triangle O A B is 
equal to the total horizontal pressure of the water. The area of 
any triangle is equal to one half the product of its base by its alti- 
tude. In this case the base is W h while the altitude is h, and half 
the product of these two is equal to -J W h 2 which is identical with 
the result previously arrived at in another manner. 

Assume that the entire thrust of the water is concentrated 
at the centre of pressure which corresponds to the centre of gravity 
of the triangle O A B. The centre of gravity of any triangle. is 
at one-third the vertical height of the triangle above the base. 
This point is indicated by g in Fig. 6. The pressure to overturn the 
dam is \ W h 2 and it has a lever arm of J h through which it acts. 
The overturning moment therefore is the product of the force 
multiplied by its lever arm = \ W 2 h X |Ij = |WE Substituting 
the value of W = 62.5 lbs., the formula becomes M = io.4 h 3 , 
M being the overturning moment of the water in pounds. In 
metric measurements this is equal to 16c h 3 kilos per metre length 
of dam where h = depth of water in metres. To resist this overturn- 
ing moment the weight of one foot length of the dam, multiplied 
by its lever arm of action, must be equal to or greater than M. 



DAMS 2 1 

Call w the weight per cubic foot of the material of which 
the dam is composed. Assume a contour or shape of the section 
of the dam and compute the area of this cross-section. The square 
feet cross- section are numerically equal to the cubic feet in one foot 
length of dam. If the cross-section of the dam is F. square feet, 
its weight per foot length will then be equal to w F lbs. 

Assume that this weight acts downward through the centre 
of gravity of the cross-section of the dam. It being still further 
assumed that when dams overturn they rotate about the rear 
lower edge or "toe," the lever arm through which the weight of 
the dam acts is the horizontal distance from the rear toe to the 
line of the centre of gravity. Call this distance L. Then wFL 
is the moment of the weight of the dam to resist overturning, and 
this should be from three to four times as great as the moment of 
the water pressure acting to overturn it. This formula also holds 
if w = weight per cubic metre, F = cross-section of dam in square 
metres and L = the lever arm of the centre of gravity of the dam 
in metres. 

In Fig. 6, A represents the location of the centre of gravity 
of the cross-section of the dam, and F is its area in square feet, 
the weight per foot length of dam being w F as shown. L is the 
horizontal distance from the toe of the dam to the line through the 
centre of gravity, and the moment to resist overturning is w F L as 
shown. 

It is not sufficient, however, to consider only the moment of the 
entire cross-section of the dam about the toe. 

Fig. 8 shows the necessity for additional computations. 

In this figure, although the area F is somewhat smaller than 
in Fig. 6, the lever arm L is greater and the product w F Lis prac- 
tically as great. The dam shown in Fig. 8, however, would fail 
by the overturning of some portion of the upper section. 

To proportion a dam properly it, therefore, is necessary to make 
computations for several sections— not less than three and usually 
five. This is done by dividing the figure into the number of hori- 
zontal sections desired. Fig. 8 is divided into three sections as 



22 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



shown, the first being from the top down to the line CE, the second 
from the top down to the line O K, and the third from top to bot- 
tom, including the entire structure. Considering now the first 
section, the overturning moment of the water is 10.4 h*. h t 
being the depth of water down to line C E. Call the area of sec- 




Fig. 8. 



tion of the dam DEC included between the upper edge and the 
line C F equal to F and the horizontal distance between its centre 
of gravity and the rear face of the dam where C E intersects it 
equal to L p the weight per cubic foot of material being w, then 
the resistance of the upper section to overturning about the line 
C E is w F x L x and this must be three or four times as great as the 
overturning water pressure 10.4 h*. Similarly the overturning 
water pressure about line S K is 10.4 h 2 3 , h 2 being the depth of 
water down to line S K. The resistance to overturning is w F 2 L 2 
in which F =area of section from the top down to line S K, 



DAMS 



23 



and L 2 is the horizontal distance of the centre of gravity of this 
section from the rear surface of the dam. In the same manner 
the total water pressure and resistance of whole dam are com- 
puted. All the computations should show the dam amply strong 
at every point. If any section taken shows too small a re- 
sisting moment the dam must be thickened at that section until 
the calculations show it to be safe. There are mathematical for- 
mulae for computing the contour or form of the cross- section of a 
dam made of any given material, but the easiest, safest, and 
simplest way to lay out the cross-section is, by first assuming a shape 




and then computing the relative overturning effects of the water, 
and the resistance of each of several sections of the dam as before 
indicated. By altering the different sections to correspond to the 
computed requirements, making thicker in some places and thinner 
in others, a proper form of cross-section can be obtained. 

One of the general rules in designing dams is to take the re- 
sultant of the overturning force and the opposing stress, and note 
where this resultant intersects the bottom line of the dam. If 
the intersection falls within the middle third — i.e., the middle one 



24 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



of three equal lengths into which the bottom line of the dam con- 
tour is divided — the dam is considered safe. Thus in Fig. 9, G 
is the centre of gravity of the cross-section of the dam, and the down- 
ward vertical line G M passing through the centre of gravity rep- 
resents to some scale the value of w F or the weight of the dam 
per foot length, while G N, also passing through the centre of gravity 




Fig. io. 

and at right angles to G M, represents to the same scale the value 
of the water pressure per foot length of dam = 10.4 h 3 . Com- 
pleting the parallelogram on G M and G N their resultant is G R, 
intersecting the base line at O which is well within the middle 
third. 

This method of determining the stability of a dam is applied 
also to separate sections as previously described. 

When dams are constructed with the up-stream face sloping, 
the stability is greatly increased, as the weight of the water tends 
to hold the dam against overturning. Thus in Fig. 10, if K L M N 



DAMS 25 

be the contour of the dam, the centre of gravity, found by the con- 
struction before described, is at G. 

The downward force acting at G due to the weight of the dam 
is G Y. A B is the horizontal pressure = 10.4 h 3 acting hori- 
zontally at a distance of J h above the bottom of the dam, while 
g A is the vertical pressure of the water = J W J hor 3i.2$XjXh 
acting downward through the centre of gravity of the triangle 
L F K which represents the mass of water supported by the 
dam W being the weight per cubic foot of the water. The re- 
sultant of these two forces is found by completing the parallelo- 
gram A B c g. It is equal, algebraically, to 



\/ (km *7 + (31.25 h iy 



but it is easier to find this value graphically, which from the 
figure is equal to g B and has a direction perpendicular to K L. 

To find the effect of this resultant force on the stability of the 
dam, combine it with the force due to the weight of the dam 
acting through the centre of gravity G, and equal to G Y. 
From point O where G B extended intersects G Y, extend G Y to 
S, O S being equal to G Y. Draw S V equal to g B and com- 
plete the parallelogram. The resultant is O V, which cuts the foot 
of the dam nearly underneath the centre of gravity and thus shows 
a large factor of safety. 

In designing dams special care must be given to three important 
factors which are : — 

(1) The spillway — i.e., that portion of the dam over which 
the excess water pours — must be sufficiently long to pass over it all 
the water in time of heaviest flood, without the water rising too 
high in flowing over it. For this reason it is not always best to lo- 
cate a dam in the narrowest part of a stream, as the spillway might 
be too short if the stream were subject to heavy floods. Whether 
a dam can be made very short or not depends largely on the varia- 
tion in flow during the year and particularly on the maximum flow. 

(2) The dam in every case, no matter how constructed or 
of what material, must rest on a solid foundation. All earth, 



26 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



sand, loose rock, and other removable materials on the river bot- 
tom should be removed and the river bottom excavated until rock 
or hard-pan is reached. Too much care cannot be exercised 
in this matter. Usually after reaching rock bottom a shallow 
channel should be blasted out in which the bottom of the dam 
may rest. Failure to provide proper foundation will result in fail- 
ure of the dam, no matter how well it may be built otherwise. 

(3) Proper provision must be made for preventing the falling 
water, which pours over the spillway, from washing out the founda- 
tion or eroding the dam itself. Usually the dam is constructed 




Fig. 11. 

to carry the water down gently either on an incline or a curved 
surface, or in some kinds of timber dams the rear face is a series 
of short steps, so that the water falls easily from one level to the 
next. 

There are several types of dams, and the construction adopted 
depends on the size, height, materials available, character of the 
stream bed, and the fluctuation in the stream flow. All these con- 
siderations are modified by the funds available and other com- 
mercial factors. 

The dams in general use are: earthen, timber, masonry, and 
reinforced concrete. 

Earthen dams are unsuited for any situations except for very 
low, short, deflecting dams where they serve merely to turn the 



DAMS 27 

water into a canal or pipe. In no case can they be successfully 
used where the water ever passes over the crest. Their height 
should never exceed forty feet unless they are reinforced by an in- 
ternal core wall of brick or masonry. If thus strengthened the 
height may be carried up to sixty feet. 

Fig. 11 shows the general dimensions of an earthen dam hav- 
ing a masonry core. 

If h = height of the dam, the thickness through at the toe or 
bottom should be 2.5 to 3.5 h, and the top thickness should be 
not less than 0.4 h. Thus for a dam 12 feet high, h=i2. Thick- 
ness through at the bottom = 25 X 12=30 feet. Thickness at 
top = 0.4 X 12 = 4.8 feet = 4 feet 10 inches. The thickness of 
masonry core walls should be approximately as follows: 

For dams up to 15 feet high 18 inches 

" " from 15 feet to 25 feet high 24 " 

" « 25 " "40 " " 30 " 

The best material for earthen dams is a mixture of gravel and 
clay. Almost any proportions of mixture will make a good dam, 
though one- fourth clay to three-fourths gravel is a common propor- 
tion. Colonel Fanning recommends as a standard mixture the 
following, all proportions being by measurement: 

100 parts coarse gravel 
33 " fine gravel 
15 " sand 
20 " clay 

Timber dams can be used in nearly any situation. They have 
the merit of being cheap, easy to build, and quickly put in place. 
They have the disadvantage, however, of requiring frequent re- 
pairs above the water-line. Of course those portions that are com- 
pletely submerged will last indefinitely. They cost from one-third 
to five-eighths as much as a good masonry dam, depending on the 
locality. In many cases they serve the purpose admirably and 
enable a development to be made and put in commission where the 
expenditure would be prohibitive if a masonry dam were erected. 
Their forms are numerous, and could not all be here given in 



28 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



proper detail, but nearly any engineer or constructor can design a 
wooden dam to resist the forces it may be subjected to. 

Examples of timber dams are shown in Figs. 12 and 13. Fig. 
12 shows a crib dam, made by piling up logs in square " cribs" 




Fig. 12. 

and filling these in with loose stone. The upper surface is covered 
with planking two inches thick, and the rear of the dam forms a 
succession of steps whereby the overflow water falls gently to the 
lower level of the tail race. 

Fig. 13 shows another form of wooden dam, called a frame dam. 
The dimensions are given and the construction is obvious from the 




Fig. 13. 

figure. The framework is filled with loose stone or gravel and 
covered over with planking. 

In many instances where the maximum floods are small and 



DAMS 



2 9 



the river is wide, earthen dams are built nearly all the way across 
the stream and timber spillways fill the rest of the space, and thus 
a combination earth-and-timber dam is formed. The earth por- 
tion must be enough higher than the timber part to prevent water 
from ever passing over the former, all water flowing over the tim- 
ber part only. The excess height of the earth dam above the tim- 



w%mmm$3w 




Fig. 14. 



ber spillway depends, of course, on the length of the spillway and 
the maximum flow in time of flood. 

Masonry Dams. — These are the most generally used, and, though 
the most expensive, are the most reliable and satisfactory, requir- 
ing a minimum amount for repairs and maintenance. 

Fig. 6 shows the usual form of cross-section of a masonry dam. 
As will be seen, the rear face of the dam is curved in such a manner 
that the overflowing water follows smoothly down against the rear 
face, changing its direction continually and finally reaching the tail 
water without impact. The two curves which are reversed to each 
other, and which outline the shape of the rear wall, are parabolas. 

Masonry dams have their approximate contours computed as 
before outlined in this chapter, and the smooth curves are drawn 
to adhere as closely as possible to the computed outline. 

The materials used in dams of this type are widely variable. 
Some are made of cut stone, laid up in hydraulic-cement mortar. 



3° 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



A usual construction is to lay up the front and rear walls of cut 
stone, and fill in between these with concrete. 

Cyclopean masonry is also used in some instances. This is 
made up of rough stones of various sizes and shapes, ranging 
from the size of a barrel down to the size of a man's fist. The 
smaller stones fill the interstices between the greater stones, all 
being laid in Portland- cement mortar. 

Some dams are now made altogether of concrete, which is 
firmly rammed, as the construction proceeds, to solidify the mass. 




Fig. 15. 

More recently the growing use of steel-reinforced concrete has ex- 
tended to hydraulic work, and the dams are strengthened by the use 
of reinforcing steel forms. These concrete dams are of the so-called 
" gravity" type. That is, they have a sloping face on the up- 
stream side, and use the downward thrust of the water to give 
stability to the structure. In this way the weight of the dam may 
be greatly diminished and the cost proportionally decreased. 
Fig. 14 shows a section through a dam of this character. As may 



DAMS 



31 



be seen, it is hollow and depends for its effectiveness on the weight 
of the water rather than the absolute weight of the dam itself. 

Fig. 15 is a masonry dam in the course of construction, its 
general form being that indicated in Fig. 6. Fig. 16 is a picture of 
this dam completed, with water pouring over the spillway. The effect 
of the curved rear face in carrying the water smoothly down is seen. 

Dams must always be constructed with drain gates near the 




Fig. 16. 



bottom, so that, in case of repairs being necessary, the water may 
be drawn down and the entire reservoir drained. Usually these 
gates slide upward to open, being moved by a rack and pinion 
or, in some instances, a screw. 

A drain gate should also be provided near the top of the dam, 
to allow accumulated trash and floating debris to pass through 
whenever this upper gate is opened. This gate also helps to dis- 
charge water in time of heavy flood. 



CHAPTER III. 
Canals and Flumes. 

When the location of a dam is decided on, if it be at the foot 
of the fall or shoals, the power-house too will be located there, and 
no conducting of water will be necessary. If, however, the dam 
is placed some distance above the foot of the shoals, the water 
must be conducted to the power-house, which is always at the foot 
of the fall. The oldest method of carrying the water is by means 




Fig. 17. 

of a level canal running along the hillside until the power house 
is reached, and then being carried down through a pipe to the 
water wheels. Where necessary for the canal to cross gulleys, 
ravines, or other depressions, the crossing is made by means of a 
trough or flume supported on a trestle-work. Fig. 17 shows a 
wooden flume carrying water across a depression. Except under 
unusual conditions, however, it is better and cheaper to use pipe 
to convey the water to the power-house. The pipe does not have 
to be laid level, but can follow the contour of the shortest route 
from the dam to the power-house. For small powers, cast-iron 

3 2 



CANALS AND FLUMES 



33 



pipe is sometimes used; for large quantities of water, wrought-iron 
pipe is employed, while for low head, wood stave pipe held together 
by iron bands is used. 

In some cases that portion of the pipe near the dam and where 
the pressure is low — say up to forty feet head — is made of wood stave 
pipe, while the lower portion of the conduit is made of riveted 
wrought-iron pipe, which gradually increases in thickness as the 
pipe sinks further and further below the reservoir level, that is, as 




Fig. i 8. 

the pressure on the pipe increases, the strength of the pipe is in- 
creased. 

Fig. 1 8 shows a wood stave pipe which forms the upper or low- 
pressure portion of a water conduit for a power station in the 
Western States. 

Riveted wrought-iron pipe costs about double that of wood 
stave pipe. Following is a table of approximate costs per foot of 
riveted pipe of various diameters, to withstand pressure due to 
250 foot head. 

These costs change with increase or decrease of head. The 

figures are based on a unit price of 4j cents per lb. To compute 

the weight of any pipe take the circumference X length. This 

gives the area in square feet. Multiply the area by 2.5 and this 

3 



34 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

product by the number of i6ths of an inch thickness of the plate. 
Add to this 10 per cent, for lap and rivets. Thus a pipe 60 inches 
in diameter and T \ inches thick weighs per 100 feet: 100 X 3.1416 
X fl X 2.5 X 5 = 11,881 lbs. Add 10 per cent, and the total 
weight becomes 13,069 lbs. 

Table No. 2. — Costs of Steel Pipe. 

Inches 



Inches 

10 $ .72 

12 82 

14 98 

16 1.20 

18 1.40 

20 2.00 

22 2.25 



2 4 $2.35 

26 2.60 

28 3-oo 

3o 3- J 5 

36 500 

40 6.40 

42 7.00 



The transmission of water through pipes is accompanied by 
a loss of head and this loss means that, for a given quantity of water, 
less power is available at the water wheels. The larger the pipe 
the less is the loss of head, but the greater is the cost of the pipe. 
Therefore, this feature brings in another commercial factor as 
to the size of pipe which represents the smallest loss of power and 
interest on the invested capital. Where the power is small and its 
value high, more money can be invested in pipe than where the 
power is great and its value low. The average size of pipe adopted 
in the United States is that which gives a velocity of water of from 
4 to 6 feet, or from ij to 2 metres per second. Velocities as low 
as two feet (0.6 metre) and as high as 12 feet (3.6 metres) per 
second are known, but the figures given represent fair average 
practice. 

If Q = quantity of water in cubic feet required per second 
for a given turbine under a specified head, the diameter of the pipe 

required with a given velocity is D = i.i37|/_-^. in which Q = 

quantity of water flowing in cubic feet per second, V = velocity 
of flow in feet per second. This formula also holds for metric 
measurements. If D = diameter of pipe in metres, Q = cubic metres 
of water per second, and V= velocity in metres per second. 



CANALS AND FLUMES 35 

The loss of head is computed from the formula 

■)IV 2 



/*=(-—- +0.0234 V 2 ), 
v lod ' 



in which 

h = loss of head in feet ; 

/=a variable factor depending for its value on the character of the 

pipe surface; 
/ = length of pipe in feet ; 
d= diameter of pipe in feet; 
V = velocity of now of water in feet per second. 

Values of / are as follows : 
For smooth-planed wood-stave pipe = 0.005 I i-J -J; 

For smooth-steel plate pipe = 0.0065 ( 1 -f- — — j ; 

For old and pitted steel pipe = 0.01 ( i-f- I. 

V i2d/ 

In arriving at the actual head acting on the water wheels the 
frictional head loss, computed as above, must be deducted from 
the total head to obtain the net effective head. 

Where an open canal is used to convey the water to the power 
station, it is often practicable to make the side next the stream 
assist the spillway by constructing it to allow water to flow over 
the edge without injury to the canal bank. In such cases very 
short dams may be used, the length of spillway being made suf- 
ficiently great by using the side of the canal. 

At the point where a canal joins the dam and the inflowing 
water enters, it should be protected against both heavy and 
light trash which floats down stream and accumulates. Stop logs 
placed out a few feet from the canal mouth serve to arrest the en- 
trance of heavy timbers or branches of trees. These stop logs are 
simply booms made of heavy wooden timbers laid across the stream, 
which float on the water, but are anchored to prevent them from 



36 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

moving from their positions. Trash racks must be put in place 
to stop the smaller and lighter trash, such as twigs, and particularly 
dead leaves. These trash racks are made of flat rectangular bars 
of iron or wood — preferably the former — which are put in an almost 
vertical position with the narrow edge to the inflowing water, each 
bar extending from a point four or five feet below the surface of 
the water to about five feet above it. The bars are spaced from 
1 to 2 inches (2 J to 5 cent metres) apart and are fastened together 
to form sections, each section being from 2 to 3 feet wide. These 
sections, which are in effect vertical gratings, are held by a frame- 
work which is generally arranged with slides, so that each section 
may be hoisted up and cleaned when necessary, and afterward 
slipped back into place. 

Forebays should also be provided. These are sin ply quiet 
ponds which are made by running low walls out into the water 
from the mouth of the canal, the walls spreading further and fur- 
ther apart as they extend outward. It is also customary to pro- 
vide a forebay at the lower end of the canal, made by widening 
out the canal to three or four times its normal width, just at the 
power-house. The length of the forebay is about the same as its 
width. Its object is to allow the water to enter the water wheels 
smoothly and easily without eddy swirls; and it is simply a basin 
of sufficient volume to allow the incoming water, rroving at some 
velocity, to settle quietly before going to the water wheels. 

A second trash rack should be placed at the power station 
between the forebay and the entrance for the water to the turbines. 

When closed pipes are used, a forebay, trash racks, and stop- 
logs must be provided at the mouth of the pipe, but none, of course, 
at the power station. In addition, provision must be made to 
prevent injury and possibly rupture of the pipes from water ham- 
mer, which occurs when the turbine gates tend to close too quickly 
unless some preventive measure is taken. 

There are two methods of preventing water hammer. One is 
by means of relief valves, which are simply spring pressure valves 
very similar to an ordinary pop safety valve for steam boilers. 



CANALS AND FLUMES 



37 



These open when the pressure in the pipe increases. They must 
be of ample area. Generally several are used, located at the lower 
end of the pipe, and their combined areas should be equal to at 
least thirty per cent, of the area of the pipe. 

The other method is the use of a standpipe. This is a verti- 
cal pipe connected with the main pipe at a point near the lower 
end of the latter. This standpipe is open at the top and therefore 
must be high enough to be on a level with the surface of the head 
water or slightly above it. If the pressure in the pipe is normal, 
the standpipe simply remains filled to the top. A sudden increase 
in pressure in the main pipe line, due to sudden closing of the tur- 
bine gate, will cause water to flow up through the standpipe and 
pour over the top, the main pipe pressure having risen above that, 
due to the head of water in the standpipe. The area of the stand- 
pipe should be not less than thirty per cent, of the area of the main 
pipe, and fifty per cent, is better. 

Obviously, since a standpipe must be as high as the head of 
water available at the power station, it is suited only to use on low 
heads, say not above 60 feet. It must be well braced against 
swaying, securely fastened in place, and provision must be made 
to catch and carry away its overflow. The water from it falls 
through a considerable height and will quickly erode foundations, 
concrete work, and the like if allowed to fall against any such struc- 
tures. 

For the benefit of those who are interested in following further 
the question of pressures set up in pipes with rapid closing and 
opening of water gates, an abstract of a paper on this subject, 
presented before the American Institute of Electrical Engineers 
by the author, is inserted as an appendix to this text. 



CHAPTER IV. 
The Design of Hydro-Electric Power-Houses. 

There are three general classes of power-houses. The first 
is that which is located at some distance away from the dam and 
the water conducted to the power-house, the flow of water being 
from the front to the back of the house, passing transversely 
under it. 

The second is that in which water is conducted to the power- 
house, passing through water wheels located outside the house, 








W'Vm 



IllplAlltli 



*$ezit^i 




Fig. 19. 

the flow of water being alongside and parallel to one of the outer 
walls. 

The third is that in which the power-house is located at the 
dam, the water passing through the water wheels and transversely 
under the house. 

In the first and third types, the houses are built on a series 

38 



DESIGN OF HYDRO-ELECTRIC POWER-HOUSES 



39 



of arches of masonry or concrete running transversely under the 
floor and which are sprung from piers that, in turn, rest on the 
foundations below. Usually the piers extend transversely the 
whole width of the house. 

The floor of the house is constructed on the arches, by filling 
in over them with masonry or concrete until a level surface is 
obtained. 

In cold climates where there is liability of freezing, the wheels 
are placed inside the power-house, but in warmer latitudes they 




Fig. 20. 

are put outside, with the stuffing-box end only of the casing passing 
through the wall and flush with the inner face. 

The turbines are supported on masonry or structural steel 
supports, or, when located outside the house, they sometimes rest 
on extensions of the arches which project beyond the wall of the 
house. The water passes through the wheels and is discharged 
through draft tubes to the tail water below which flows through 
the arches underneath the house, to the stream bed. When the 
turbines are placed inside the house they rest on the floor above 
the arches. 



40 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



The customary design provides for an arch for each main tur- 
bine and one for two small exciter turbines. Figs. 19 and 20 show, 
generally, power-houses of these types. 

Taking up the first- class and considering it more in detail it 
may be subdivided into two types, (a) one in which the turbines 
are direct-connected to the generators, and (b) that in which the 
turbines are belted or rope- connected to the generators. In the 
former case the turbines are set at such a level that their shaft 
centres coincide with the generator-shaft centres, and a flanged 
coupling connects the two shafts. The generators are usually 






r ii 


|p^^-=^=S3a5I-~S : 53 


j Canal 


Ijuuuuu 


rra^^%fc^^ 



Fig. 21. 



made with bases of such height that the distance from the masonry 
supporting floor to the centre of the generator shaft is the same 
as the height of centre of the turbine, so that the two rest on the 
same level. 

When the turbines are set inside the house, the conducting 
tubes pass through the wall or under the archways and upward 
through the floor to the wheels. If the turbines are set outside 
the house, the stuffing-box end of the casing, through which the 
drive shaft passes, is set into the wall, the end of the casing being 
flush with the inner surface of the wall or possibly projecting a 



DESIGN OF HYDRO-ELECTRIC POWER-HOUSES 



41 



few inches into the room. These remarks apply, of course, only 
to iron-shell-encased turbines. 




When the wheels are set in open penstocks of masonry or con- 
crete, one wall of the power-house usually serves as a wall of the 



42 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



penstock. Stuffing boxes fastened into the wall allow the turbine 
drive shafts to pass through into the power-house without leakage 
cf water. Fig. 21 shows a cross-section through a station using 
an iron-encased turbine inside the house direct connected to the 
generator it drives. Fig. 22 shows a direct- connected plant in 
which the turbines are located outside the house in an open pen- 
stock. The supporting arches which carry the power-house 
floor are clearly indicated in these sections. As may be seen in 





sf? 


M 1 It- m * 




"^ jig, ,. 

JS| Is 





Fig. 23. 

Fig. 21 the conducting pipe from the dam goes directly to and con- 
nects with the iron casing of the turbine. 

The use of the open penstock is confined to low heads — say up to 
thirty-five feet — and generally, the water conduit is a canal or open 
flume which discharges into the penstock, though in some instances 
pipes conduct the water to the penstock. Whenever it is feasible, 
the open penstock should be used, as the regulation obtainable 
on the water-wheels is improved and they are more accessible for 
inspection and repair. 

Some plants have the water supplied by a canal which ends 
in a forebay near the power-house, and a short tube conducts the 
water to iron-encased wheels. Power-houses for such equipments 
are similar to the arrangement shown in Fig. 21. 

Power-houses of the second class, i.e., where the discharge water 



DESIGN OF HYDRO-ELECTRIC POWER-HOUSES 



43 



from the turbines does not pass under the house, but alongside of 
it, are usually for small- capacity plants. The house may be 
supported in any manner which seems most suitable for the par- 
ticular situation, no provision being made for the passage of water 
underneath it. Fig. 23 is a view of a plant of this type. The tur- 
bines are supported on a masonry foundation extended upward 



— 33 ± 



Ei.121.0 



Ei.102.0 




Fig. 24. 

until its surface is approximately level with the power-house floor. 
An archway in the water-wheel foundation provides for the dis- 
charge of water. 

Fig. 24 is a cross- section of this plant, showing the building walls 
and the supporting piers for the generators, running down to bed- 
rock. 

For small plants in warm or temperate climates this is an ex- 
cellent and low-priced form of construction. 



44 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

The most general construction at present in favor is to build 
the power station at the dam, when possible, and to let one wall 
of the power-house be close to the dam, and in some cases the rear 
of the dam forms one wall of the house. This portion of the dam 
is not made in the same form as the rest, but rises much higher than 
the crest of the spillway portion and is simply shaped to give the 
requisite resisting strength, not curved to carry away overflow, since 
there is no passage of water over this portion of the dam; in fact, 
the added height is for the purpose of preventing any overflow 
at that end. This raised portion is called the bulkhead. 

The turbines used in such cases are almost invariably iron- 
encased, their shells being extended to pass through the bulkhead 
and receive the water direct without the necessity of using conduct- 
ing pipes of any kind. 

When the bulkhead serves as the power-house wall, the tur- 
bines are placed inside the house, their casing extensions passing 
through the bulkhead and being sealed into the masonry. The 
turbine end of the casing being inside the power-house, the wheels 
themselves are accessible for repairs. 

In some of the later plants the power-house wall is separated 
from the bulkhead, there being a short space between the two. 
The turbine casing passes through bulkhead and across the in- 
tervening space and through the wall of the house, ending just 
inside the wall or flush with it at one end, and at the inner bulk- 
head face on the other. Large openings are made in the casing, 
between the bulkhead and house wall, and through these openings 
the wheels may be inspected and repaired. They are closed up 
with steel plates bolted in place. 

The draft tubes pass down through the supporting arches — 
which are extended up to the bulkhead and joined to it — and the 
water is discharged below the floor passing under it, just as has 
been before described. 

Fig. 25 illustrates this method of construction. The level of 
the water shows the height of the spillway portion of the dam, and, 
as may be seen, the bulkhead portion is much higher than the crest 



DESIGN OF HYDRO-ELECTRIC POWER-HOUSES 



45 




46 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

of the dam. The turbine units, in this case, comprise two pairs of 
double wheels coupled tandem. 

In many instances, the low speed of the turbines due to low 
heads precludes the possibility of using low-priced dynamos if 
direct connected to the turbines, owing to their similarly low speeds. 
It therefore becomes necessary to drive the dynamos by belting 
or rope drives from the turbines, in order to give a higher speed to 
the generators than that of the turbines. In such plants it is 
customary to make the station floor considerably higher than the 
level on which the turbines rest, generally from ten to twenty feet 
higher, and have the belts or ropes pass diagonally upward from the 
turbine drive pulley to that of the dynamo. The turbines may be 
placed outside or inside the house and may be in open penstocks 
or steel-encased. Usually in such cases, however, the water-wheels 
are installed in open penstocks outside the house, and their drive 
shafts extend through stuffing boxes into the house walls. On 
the inner ends of the shafts are placed the drive wheels which 
transmit the power to the dynamos. 

When the hydraulic heads are very high, impulse wheels of 
the Pelton pattern are used, and these rotate at very high speeds. 
The impact of the water jet coming from the supply nozzles is so 
great that provision must be made to prevent the erosion of power- 
house foundations and consequent collapse of the structure. This 
is done by providing a deep, long pool of water against the sur- 
face of which the deflected portion of the jet strikes. At the far 
end of the pool is a baffle which maintains the required depth of 
water in the pool, usually from five to eight feet. The impact of 
the water from the nozzle being at an acute angle to the pool water 
surface, the jet passes a considerable distance, diagonally, before 
striking the bottom of the pool, and its velocity has practically 
been reduced to zero by the time the bottom is reached, so that there 
is no scouring or erosive action. 

Fig. 26 shows a section through a power-house of this character. 
The arrangement of impulse wheel and nozzle is clearly indicated. 

In designing power-houses care must be taken to locate the 



DESIGN OF HYDRO-ELECTRIC POWER-HOUSES 



47 



water-wheels at a proper height above the tail-water level. Where 
streams are reasonably constant in their volume of flow and the 
tail- water level does not vary greatly, the turbines should be placed 
at a height of from 8 to 12 feet — or 2 J to 3 \ metres — above the nor- 
mal level of the tail water, the distance being measured from the 
centre line of the turbine. In cases, however, where the flow of 
the stream fluctuates greatly, the tail- water level will also vary 
within wide limits and the turbines must be placed higher. The 




.k£ .^-li^-^ - i ^l 't ■ -i^rJ^-^ jS r-~H-^^icXgg= c 



Fig. 26. 



,,-■.>:: -t> .;-.:j.-- , - , v;;-y.:"iv : 



conditions in this respect, have, in some instances, required the tur- 
bines to be located twenty feet above the normal tail- water level. 
The efficiency of the draft tube begins to decrease if its length 
exceeds fifteen feet, and in no case should turbines be placed more 
than this height above normal tail-water level unless the conditions 
absolutely require a greater height. 

Power-houses are built of a variety of materials. The con- 
struction most in favor in the United States is the masonry or con- 
crete for arches, piers, and foundations, brick for the structure it- 



48 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

self, reinforced concrete for floors, and a trussed roof of structural 
steel, covered with slate, tiles, or gravel roofing. Iron or steel 
roofing is not suitable for power-houses because it "sweats" or 
accumulates condensed atmospheric moisture on the under surface. 
Whatever be the method of construction, the station should be 
made entirely of fire-proof material. 

The floor space of the station should be sufficiently large to 
admit of getting at every side and part of each machine, with plenty 
of space between machines and walls or between neighboring 
machines to easily pass round them and to remove any part with 
ease and facility. 

The height of stations varies greatly. The minimum height 
from floor to roof trusses should not be less than 18 feet, but in 
very small plants this has been made as low as 16 feet. For mode- 
rate-size stations, 20 to 22 feet is a fair height, while 26 to 28 feet 
is usual in large stations where the dimensions of the generators 
are considerable. 

The foundations should, when possible, rest on bed-rock. 
When this is impracticable or if hard-pan cannot be reached, it is 
necessary to drive piles, cut them off below the low-water level 
so that no portion of them may ever become dry, and put in a 
concrete footing on top of the piles. The number, length, and size 
of the piles depend on the character of the soil and the load to be 
carried. The usual spacing of piles is three feet between centres, 
though this is frequently varied to suit conditions. No general 
instructions can be given for this part of the work, as each case 
must be treated to cover the individual conditions that exist. 

Nearly every station is designed to carry overhead travelling 
cranes, by means of which the machinery may be erected and any 
part easily and quickly lifted out of place for inspection and re- 
pairs. This is a desirable arrangement for large stations having 
many imits, but, in the opinion of the author, it has been carried 
too far in the design of small stations. A good travelling crane 
with its runway and supporting structure is expensive, and in many 
cases the money spent therefor could be used to better advantage 



DESIGN OF HYDRO-ELECTRIC POWER-HOUSES 49 

in providing higher grade generating equipment, or letting it re- 
main unspent. A heavy set of short, strong shear legs, arranged 
in tripod form, with a differential chain hoist, is all that is required 
in small power-houses. 

The switchboard should be located on a gallery elevated above 
the floor level. The heights that are usual are from seven to ten 
feet. Underneath the rear of the gallery are placed brick chambers 
in which are located the high-tension switches, operated directly 
from the switchboard above. 

When transformers are used, they are generally located in 
the power station itself, though in some recent plants a separate 
building is provided for their reception. Each transformer should 
be placed in a separate brick or concrete chamber, well ventilated 
and provided with a fire-proof steel door at the front. The floor 
level of the transformer chambers should be the same as that of 
the station floor so that any transformer may be rolled out on the 
rollers placed under each one onto the station floor for inspection 
or repair. 

One of the important factors in hydraulic-power plant design 
is the proper provision for removal of sand, leaves, ice, and trash 
from the water flowing into the wheels. Sand is detrimental owing 
to its cutting action on the water-wheel blades; and in high-head 
plants, where impulse wheels are used and the velocity of the water 
is high, a very slight amount of sand will quickly cut through the 
wheel bucket. The usual way of removing sand is to provide 
a settling basin at the upper end of the pipe, where the water comes 
to rest and stands long enough to let the sand settle to the bottom 
of the basin. 

Surface or floating ice gives but little difficulty if the conducting 
pipe is set into a forebay or basin, several feet below the surface of 
the water, as the ice simply covers the basin, and the water flows 
to the pipe beneath it. The so-called frazil ice, however — i.e., ice 
in finely divided form — mixes with the water and is held in suspen- 
sion and it will, therefore, pass through the pipes to the turbines 
and clog them, no matter how far below the surface of the water 

4 



5<D DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

the pipe may be placed. A large forebay or settling basin at the 
power-house is required to prevent the inflow of this frazil ice. It 
slowly floats upward, freezing solid at the surface, and in this way 
the water is cleared. 

Accumulations of leaves are particularly troublesome, and it 
is difficult to clear the water of them. Trash racks, such as de- 
scribed in the foregoing chapter, will prevent them from getting to 
the wheels, but the racks themselves become clogged and require 
continual cleaning ; in some cases two men are kept busy continu- 
ously clearing the racks. 

Specially designed forms of moving-chain conveyors which 
allow the water to pass through them, but catch and elevate the 
leaves, discharging them onto a platform or to one side of the flume, 
have been used with success. There is no standard device, how- 
ever, for this purpose, and each case must have the design made 
to suit the individual conditions. 



CHAPTER V. 

Water- Wheels. 

Water-wheels may be divided into three classes, viz., pressure 
turbines, impulse turbines, and Pelton or jet wheels. 

The pressure turbine consists of a rotating wheel having curved 
vanes or buckets attached to its periphery, and stationary vanes 
which serve to direct the flow of water into the wheel buckets. The 
forms of the guide vanes and the wheel buckets are such that the 
water enters the openings without appreciable impact, but guided 
in a particular direction and having a certain velocity of flow. 
The wheel buckets change the direction of flow of the water, and 
it is this reaction, due to changing the direction of motion of the 
mass of water, that produces the turning effort on the wheel. There 
are many designs for forms of buckets, and most of the success- 
ful ones have curvatures in two planes so that the water is received 
at the level of one plane and rejected at a lower plane, its direc- 
tion of motion continuously changing throughout its path through 
the wheel buckets. 

The wheel and guide buckets may be in the same plane, the 
stationary guide buckets being inside the periphery of the wheel, 
the water being received through a central opening and dis- 
charging radially outward. This type is termed the outward-flow 
turbine. If the guide vanes are placed above the wheel so that 
the direction of flow of the water is parallel to the wheel axis and 
perpendicular to the wheel, it is called a parallel-flow turbine. 
The inward-flow turbine has its guide buckets outside of and 
surrounding the wheel, the water passing inwardly and radially 
toward the axis. A very successful form of wheel or runner is 
shown in Fig. 27, which is the type of wheel most largely used 

51 



52 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 




Fig. 27. 



in the United States. It combines the features of inward and 
parallel flow, the water passing to the wheel inwardly and radially, 

and being discharged from it down- 
wardly and parallel to the wheel 
shaft. 

Any of these wheels may be set 
with their axes either horizontal or ver- 
tical, provided a depth of not less than 
six feet of water is obtainable above 
the upper surface of the wheel when set 
horizontally. It is customary to em- 
ploy vertical wheels for heads of less 
than twenty feet, although horizontal 
wheels have been placed and success- 
fully operated under heads as low as fourteen feet. 

With pressure turbines it is not necessary to set the turbine 
down at the level of the tail water in order to get the full effect of 
the total head. As before mentioned in describing power-house 
construction, pressure turbines may be set anywhere from two to 
twenty feet above the level on the tail water if an air-tight draft tube, 
leading from the wheel discharge down below the level of the tail 
water, be provided. This is due to the fact that the submerged 
end of the tube is sealed, and the falling water in the tube from the 
turbine discharge tends to create a vacuum in the draft tube, 
which has the effect of sucking the water through the turbine 
and adding a pressure to the inflowing water proportional to the 
vertical height of the draft tube. 

The usual speed of pressure turbines is such as to give a periphe- 
ral velocity of the wheel equal to approximately three-fourths of 
the spouting velocity of the water under the head applied. Re- 
cently, however, certain high-speed turbines have been produced in 
which the peripheral speed of the wheel is equal to 90 to 95 per 
cent, of the spouting velocity of the water. The spouting velocity in 

feet per second is equal to 8 V Head in feet. 

The variation in the power of the wheel, under a given head, 



WATER-WHEELS 



53 



for variations in load is effected by varying the amount of water 
admitted to the guide buckets or to the wheel buckets. There 
are three types of variable gates, viz., the cylinder, the wicket, 
and the register gate. 

Cylinder gates are simply sheet-iron cylinders which surround 
the stationary guide buckets. These cylinders are movable in a 
direction parallel to the wheel axis. In one extreme position the 
openings to the guide vanes are completely covered; in the other 
extreme position they are completely uncovered. As the cylinder 
moves to different positions between these extremes, the areas of 
the openings are correspondingly varied. 

The wicket gate is arranged as shown in Figs. 28 and 29. 




Fig. 28. 



In Fig. 28 is shown the moving mechanism, while in Fig. 29 is shown 
a sectional plan. In this arrangement the guide vanes are pivoted 
so that they may have their positions shifted. Each vane pivot 
has a crank arm attached to it, and an iron rod is connected to each 



54 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



of these cranks. The iron rods all have their ends attached to a 
flat central ring of iron. When this central ring is rotated through 
a small angle, the guide vanes are caused to approach toward or 




MOVING GUIDES 



Fig. 29. 



recede from each other, thereby varying the area of the openings 
through the guide vanes. 

The register gate is made of an iron cylinder surrounding the 
guide vanes and having a series of openings cut into it the size 
and form of which correspond to the size and form of the openings 
between the guide vanes. In the position where the openings in 
the cylinder correspond exactly with those between the guide vanes, 
the full flow of water passes to the wheel. If, however, the cyl- 
inder be rotated through a small angle so that the position of the 
openings in it does not correspond with the position of the open- 
ings between the guide vanes, the latter will be closed up either 
partially or wholly, depending on the amount of rotation of the 



WATER-WHEELS 



55 



cylinder, and thereby the flow of water to the wheel may be varied 
as may be desired from zero to a maximum. 

Of these gates the wicket gate is most used and is probably 
the most satisfactory, especially when the gates are to be controlled 
by an automatic governor. The cylinder gate is also a good form 
of gate for automatic governing. The register gate is not to be 
recommended except when the water is free from sand and grit 
and the governing is to be done by hand, as it is subject to rapid 
wear in gritty water, and the friction between it and the guidc- 
vane structure is too great to admit of rapid movement with ease. 

There are two methods of supplying water to pressure tur- 
bines; one is to set the wheel in a large chamber, open at the top, 
which communicates with the head water and is filled up to prac- 
tically the same level as the head water, completely submerging 
the wheel. The discharge water is taken from the wheel through 
the draft tube, which passes through the bottom of the chamber 
and is sealed in the bottom so that none of the water can pass from 
the chamber through this opening; the only possible path for the 
water being through the turbine and out by the draft tube. This 
is called an open-penstock setting. Where heads are low, say up to 
thirty feet, this is the best possible method of placing a turbine. 
Where the turbine is vertical, the shaft projects upwardly, rising 
above the surface of the water, and from its upper end power may 
be taken. When the turbine is set horizontally, the shaft passes 
through the side of the chamber, a water-tight stuffing box be- 
ing placed around the shaft to prevent leakage. Fig. 30 shows 
the arrangement of a pair of horizontal turbines set in an open 
penstock, the shaft passing through the stuffing box in the side. 

Penstocks may be made in any manner and of any material 
which will be water-tight. In some cases they take the form of 
large square wooden boxes. Usually, however, they are made of re- 
inforced concrete. In every case they must be sufficiently strength- 
ened and braced to resist the water pressure which tends to bulge 
the walls out and burst them apart. Where several turbines are 
installed, it is advisable to separate the penstock into as many 



56 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



divisions as there are separate turbine units. Normally, the di- 
vision walls will be subject to no bursting stresses, as the height 
of water is the same on either side, and the water pressure is thus 





Fig. 30. 

neutralized. If, however, it becomes necessary to inspect any 
particular turbine or make repairs on it, the water in this division 
of the penstock must be drawn off. This leaves the walls of the 
empty division subjected to the pressure of the water from the 
adjacent compartments, and it is therefore necessary to construct 
these division walls with the same strength as if they were separate 
penstocks. 

The other method of setting pressure turbines is to enclose 
each unit in a steel casing, into which water is conducted by 
means of a pipe leading to the head water. The draft tube is 
taken out through the end of the casing or down through the bot- 
tom, depending on the form of water-wheel used. This method 
of installing has certain mechanical advantages. It is very con- 
venient and occupies less space than does the open penstock, and 



WATER-WHEELS 



57 



is the only suitable and commercial method for heads above thirty- 
five feet. The speed regulation and the efficiency attainable are, 
however, not as good as with the open-penstock setting. 

The pressure of the water against the wheel is principally 
radial, but there is considerable pressure also exerted in a direc- 
tion parallel to the wheel axis, and this requires that turbines be 
provided with thrust bearings to take this longitudinal pressure. 

In order to neutralize this pressure and also to obtain high 
rotative speed under a given head, it is customary to place two water- 
wheels on a single shaft, each wheel having half the power that 
it is desired for the unit to supply. Since the longitudinal press- 




Fig. 31. 



ures act in opposite directions, they neutralize as desired; and as 
each wheel gives only half the power required, its smaller size 
gives a higher rotative speed. When set in an open penstock, 



5« 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



these wheels are supported by a draft chest which rests on the 
bottom of the penstock and to which the draft tube is attached 
that takes the discharge from both wheels. Such a setting is 
shown in Fig. 30. Obviously, a pair of wheels with their draft 
chest instead of being set in the open penstock may be encased 
in a steel shell as indicated in Fig. 31. 

In many cases where double units are encased in a cylindrical 
steel penstock, the water, instead of flowing from either end toward 
a common central draft chest, flows from the middle toward either 
end and discharges through two draft tubes as shown in Fig. 32. 
The large, ninety-degree elbows at either end of the casing are called 
''quarter turns," and in each is placed a stuffing box to allow the 




Fig. 32. 

turbine shaft to pass through. This form possesses several ad- 
vantages over the central-draft-chest arrangement. Its first cost 
is from 25 to 30 per cent, less than the cost of central-draft-chest 
turbines of the same power, its efficiency is from 2 to 5 per cent, 
greater, and it may be supported by piers or pillars directly under 
the turbine casing and wheels. Therefore this type should be 
used whenever possible. 



WATER-WHEELS 59 

The efficiency of pressure turbines when new and in good 
condition is about 80 per cent, at J gate. This efficiency usually 
falls off at full gate and below J gate. Also, in the course of time, 
the buckets become worn by the action of the water, grit, and 
other substances which are carried into the wheel, and both the 
power and efficiency are reduced. This is important and should 
be borne in mind when deciding on the size of wheel necessary 
for any given service. At least 12 \ per cent, excess capacity should 
be allowed to admit of good regulation under varying loads and 
to compensate for this reduction in power which takes place in 
the course of time. 

Pressure turbines may be obtained in standard designs for 
heads up to 100 feet. Specially designed wheels for heads up to 
160 feet are supplied by various makers. When heads are greater 
than 160 feet impulse turbines or impulse wheels should be 
used. 

Draught tubes should be proportioned so that the velocity of 
the water in them is about five feet per second when the turbine is 
developing full power. When the velocity is less than two feet 
per second the vacuum is not so good as at somewhat higher veloci- 
ties and where water-wheels are subjected to varying loads it is 
possible to get too low a velocity in the draught tube at one-third or 
one-half gate. Of course, if wheels are designed to run on steady 
loads, the velocity for full gate may be somewhat lower than the 
figure given, but in any case the loss of head in a draft tube even 
at velocity of 6 or 7 feet per second is practically negligible, and as 
a general all-round figure, 5 feet per second is about the best. 

Draught tubes should taper and have a greater diameter at the 
bottom than at the top. The diameter at the bottom should be 
about 25 per cent, greater than the diameter at the top, and the vel- 
ocity of 5 feet per second should be taken for the upper or small 
cross-section. The lower end of the tube should be submerged 
at least 8 inches and in large draught tubes — say 8 feet in diam- 
eter and above at the bottom — they should be submerged not less 
than 20 inches. 



60 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

A difficulty that frequently confronts the designer of a plant 
is that of a low head greatly influenced by floods, where the tail 
water backs up in time of flood and materially reduces the effect- 
ive head. Under these conditions there is an abundance of 
water available, and the water-wheels can work if necessary at a 
low efficiency. The power and speed must be maintained the same 
as when the normal head is acting. 

Many complicated methods of involving gears, belts, and other 
devices have been suggested. It is the author's practice, however, 
to use extra turbine wheels or runners on the same shaft, sometimes 
fastened solidly on and sometimes connected or disconnected 
by means of a jaw clutch coupling. For instance, if the normal 
head is 36 feet, with a depth of 6 feet in the tail race, and the 
flood raises the depth in the tail race to 18 feet, making the net 
head 24 feet, there should be three horizontal turbines on a single 
shaft. Assume the power to be developed as 500 H.P. Then two 
of the turbines running at full gate should give approximately 
575 H.P. under a 36-foot head, and at J gate they will give 500 H.P. 
Under 24 feet head at full gate, they will give only 312 H.P. the 
power of a turbine being not proportional to the head but to the 

A/Head 3 . The third wheel, therefore, must give 188 H.P. under 
24 feet head. When the head is normal this third wheel is idle, its 
gates are closed, and it merely rotates on the shaft with the other 
wheels. 

The speed varies as the square root of the head. At 36 feet, if the 
speed is 280 r.p.m.,at 24 feet head, it will tend to fall to 229 r.p.m. 
If the velocity of the wheel buckets is 75 per cent, of the velocity 
of the water at 36 feet head, and a 5 per cent, fall in speed at high 
water is allowable, the rotative speed of the wheel is 280 — 5 per 
cent. = 266 r.p.m, the peripheral velocity of the wheel will be about 
84 per cent, of the velocity of the water when working under the 
lower head. The two main wheels therefore should work with 
their highest efficiency at J gate with a peripheral velocity of 75 
per cent, of the velocity of the water under 36 feet head = . 75 X 8 X 
^36 = 36 ft. per second; while they should be able to give ap- 



WATER-WHEELS 6 1 

proximately their full proportional power when running at 85 per 
cent, of the • velocity of the water, and the third wheel should be 
proportioned to work under the lower head. 

Sometimes the conditions are even worse than the above case, 
and it may become necessary 7 to install two turbines on a single 
shaft, one of which gives the necessary power and speed at the nor- 
mal head, the other giving the proper power and speed at the low 
head. The peripheral velocity of the smaller wheel for the high- 
head service may be greater than the velocity of the water at the 
low head, in which case the gates of this wheel must be completely 
shut at times of high water, as it not only would not assist the low- 
head wheel, but would be a drag on it, using up instead of giving 
out power. 

Another method of arranging turbines to compensate for varia- 
tion in head is to place two units in separate steel casings or pen- 
stocks, each having its pipe connection to head water and its draught 
tube, both wheels being on the same shaft. Additional pipe con- 
nections are made and valves put in at proper points, which allow 
the shutting off of one draught tube at the bottom and turning the 
water from the closed draught tube into the case of the adjacent 
turbine. A valve in the flume or pipe line leading to this second 
unit, cuts off the water from the source of supply. With both 
valves open each turbine receives water from the flume and dis- 
charges it through its draught-tube, and, both wheels being on the 
same shaft, the power delivered is equal to the combined power 
of the two wheels, under the available head. This is the opera- 
tion at times of high water when the head is low and plenty of 
water is available. When there is but little water the valves are 
closed and the water then passes through the first turbine, into the 
second, and out through the draught tube of the second wheel. 
Obviously, the speed and power developed by these units under a 
50 foot head with 200 cubic feet of water flowing per second will 
be the same as the speed and power under a head of 25 feet and 
a flow of 400 cubksifeet per second. At intermediate stages of 
high water, betweeing. e normal and the maximum, partial closing 



62 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



of the valves will allow corresponding adjustment of the units 
for the reduction in head and increase in the volume of water. 

In some instances, owing to very low head or want of room, it 
becomes necessary to use vertical turbines. Any pressure turbine 
will work at its highest efficiency if set vertically. The difficulty, 
however, is in transmitting power to the dynamo which is usually 




Fig. 33. 

set horizontally. In the case of small units, this may be done by 
means of a quarter-turn belt or rope drive, ' 'this is not feasible 
for dynamos of above 100 kilo-watts. R r LCl itly, dynamos have 
been constructed abroad which have vertic.^d tfjs and are known 



WATER-WHEELS 



63 



as the "umbrella" type. These dynamos may be set directly 
over the water-wheels, the two shafts being connected together 
and a vertical, direct-connected unit thus produced. Fig. 33 
shows the arrangement of such units. The weight of the turbine 
runner and of the rotating part of the dynamo, together with the 
vertical shaft, form a rotating mass which must be supported. 
Step bearings and thrust-collar devices were tried for a time, but 
their excessive friction and rapid wear made the horizontal units 
far preferable when conditions allowed their use. More recently, 
hydraulic thrust bearings having but little friction and inappre- 
ciable wear have been developed and are in successful operation. 
The ability, however, to obtain standard dynamos of this type 
in various sizes and speeds is so limited that designs for vertical 
units for this character should not be attempted without first in- 
vestigating to find out if standard patterns are available for the 
sizes and speeds required. 

Many vertical turbines driving horizontal dynamos by means 
of bevel gearing have been installed and some plants of this type 
are large and important. The author's experience, however, 
with heavy bevel gears, transmit- 
ting large amounts of power, has 
always been unsatisfactory. It is 
almost impossible to keep them in 
good condition, they absorb a large 
percentage of the total energy — 
often as high as fifteen per cent. — 
and necessitate constant watching 
and repairing. No such drives 
should ever be considered except 
for temporary plants or in loca- 
tions where it is possible to use no 
other form of equipment. Under 
heads of less than 1 2 feet, however, 
vertical turbines must be used and this objectional gearing be- 
comes necessary. Fig. 34 shows a vertical turbine driving a 




Fig. 34. 



64 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

horizontal shaft by means of bevel gears and the arrangement 
is quite clear from the figure. 

The impulse turbine is but little used in the United States, 
although under certain conditions it is advantageous to install 




Fig. 35. 

them. They differ from the previously described pressure turbines 
in many respects, although they are very similar in their action. 
The wheels themselves, or runners, are provided with a series of 
curved buckets which much resemble the form of buckets used 
in pressure turbines. Instead, however, of water being admitted 
to all of the buckets, and the whole structure solidly filled, the water 
is admitted to but few of the buckets, being carried to them and 
given its initial direction by one or more nozzles. Fig. 35 in- 
dicates the general arrangement of this form of water-wheel, a 
sectional plan being shown. The water passes from the nozzle 
into the wheel buckets and after passing through the latter is re- 
jected at atmospheric pressure. Since only a few of the buckets 
have water passing through them — which in many instances does 
not fill the bucket space completely — and most of the buckets are 
entirely empty, it is, of course, impossible to use a draught tube and 
that portion of the head, from the buckets down to tail water, is lost. 



WATER-WHEELS 



65 



These wheels, when provided with several nozzles, maintain 
their efficiency over a remarkable range of load change, for the 
reason that each nozzle acts as a separate unit on that particular 
portion of the wheel covered by it, and regulation for load variation 
is obtained by shutting off one nozzle at a time, which does not, 
in any wise, affect the action of the other nozzle. Also, in varying 
the power delivered by a single nozzle, the area or spread of the 
nozzle is diminished and this simply means that the number of 
buckets acted on by the nozzle is reduced. In Fig. 35 is shown 
a movable tongue at the end of the nozzle which varies its width 
with load changes. 

The peripheral speed of the wheel is about one-half the spout- 
ing velocity of the water. As is clear from its characteristics, 
the dimensions of the wheel may be made nearly anything desired 
for a given power and head. 

Where heads are 150 feet and up to 600 feet, these wheels give 




Fig. 36. 

excellent results. Under lower heads the pressure turbine is pref- 
erable for the reasons that its efficiency at or near its rated load, 
is higher, it utilizes the total head, and is generally less expensive. 
5 



66 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



The Pelton or jet impulse wheels are suitable for heads above 
150 feet. They have the advantages of high efficiency, simplicity, 
and low cost. Fig. 36 shows the general arrangement of this form 
of wheel. The water emerges from the nozzle at a velocity equal 

to 8\/head and strikes against the wheel buckets. These are 
formed with a double curvature having a rib in the middle as shown. 
The water strikes against the sharp edge of the rib, divides in two 
equal parts, half going into one side of the bucket and half into the 
other. The water impinges against the bucket surfaces and at 
the same time sustains a change in the direction of its motion, being 
discharged by bounding back practically in the opposite direction 
to the direction of flow from the nozzle, but slightly to the side so 
that the reversed water does not encounter the incoming nozzle 
flow. The object of this design is to completely reverse the direc- 




Fig. 37. 

tion of flow of the water and have it leave the wheel at practically 
zero velocity, thus abstracting all the kinetic energy from the 
water. 

The peripheral velocity of the wheel is practically one-half the 



WATER-WHEELS 



6 7 



spouting velocity of the water, and the efficiency of this type of wheel 
is often as high as eighty-five per cent. In a wheel of given size, the 
power may be increased by simply increasing the number of nozzles, 
each nozzle adding a proportional amount of power. This in- 
crease generally is not to be carried further than five nozzles to any 
wheel, a certain distance between nozzles being necessary for the 




Fig. 38. 

buckets to clear themselves of water received from one nozzle 
before receiving water from the next adjacent nozzle. Fig. 37 
shows a triple nozzle to apply to a single wheel. When it is de- 
sired to obtain a high rotative speed with a given power, two or 
more small wheels may be placed on one shaft, each wheel giving 
its proportion of the power and the shaft velocity being that of a 
small single wheel. As in the case of the impulse turbine, the 
effective head is only that from the level of the head water to the 
wheel, that portion of the head from the wheel to the tail water 
being lost. This loss, however, with the high heads under which 
these wheels work, is a small fraction of the total available head 
and in such cases is practically negligible. 

The wheels are usually encased in an iron shell, the discharged 
water falling through the opening in the bottom of the case. The 
power is varied either by deflecting the nozzles so that only a por- 
tion of the water strikes the buckets, or by the so-called needle 
control. In this latter device a sharp-pointed, conical-ended rod 



68 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



works inside the nozzle as shown in Figs. 38 and 39, Fig. ^8 being 
a sectional view and Fig. 39 showing the nozzle with a water jet 
passing from it. The flow of water is varied by the variation in 
position of this "needle. " It must, however, be moved with com- 
parative slowness, as the rapid velocity of the water in the pipes 
leading to the wheels will cause a destructive shock if suddenly 
arrested. Relief valves must always be used in connection with 







' "- ":' ; : \ 


;'..- 






. ■ . 




.-.'.,': 






y ' ■'-\U'^i 


' 








1 j^tmm Jl 








§^^hh wn/t^^^ 



Fig. 39. 

needle nozzles. The deflecting jet, while it performs the function 
of regulation satisfactorily, is very wasteful of water under loads 
less than full load, as the flow of water is constant whatever the load 
may be 

Speed Regulation of Water-Wheels. 

There are many types of automatic speed governors for water- 
wheels, and improvements in these mechanisms are being made 
at frequent intervals. It is possible now to obtain a good regulator 
at a reasonable price. To describe the many varieties on the 
market and their methods of operation would be superfluous here. 



WATER-WHEELS 69 

It may be said, however, that they all use some form of fly-ball 
governor which, by its changes in position with speed variations, 
sets the gate opening or closing mechanism in motion. 

These governors must not move the gates too rapidly when 
the water is conducted to the turbine through long pipes, for the 
reason that the mass of water in a pipe moves with a certain ve- 
locity with a given gate opening at the turbine, and if the gate be 
closed too suddenly, the kinetic energy of the moving column of 
water must be as suddenly dissipated. The only way that this 
energy may be dissipated is by the compression of the water itself 
and distention of the pipe. Dangerous pressures may thus be 
produced unless the pipe is provided with relief valves or an over- 
flow pipe. 

Conversely, if the gate be opened too quickly, the column of 
water cannot be instantly accelerated and it tends to break in two, 
that portion nearest the wheel running into the increased opening, 
separating from and leaving the rest of the water in the pipe, which 
cannot so quickly attain the necessary velocity. As a result, a 
space is left in the pipe which is a vacuum and the external pressure 
of the air tendsto collapse the pipe. Such accidents have occurred 
and should be provided against in the design of a plant. 

A peculiar effect, quite opposite from that desired, also attends 
rapid gate movement. If the speed of the turbine decreases and 
the gate be suddenly opened to cause an increase in speed, the wheel 
will actually decrease its speed still further, for a few seconds, 
due to the decrease in pressure as above described, the effect of 
which overbalances the effect of the increased gate opening. Also, 
if the speed should increase and the gate opening be suddenly 
decreased to bring the speed back to its normal value, the wheel 
speed will increase still further, due to the increase in pressure 
set up by the suddenly arrested water column, the effect of this 
increase in pressure being greater than the effect of the diminished 
gate opening. The speed will then gradually fall until the normal 
speed is attained, several seconds being sometimes required to 
produce the proper speed change. Consequently, the governor 



7<D DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

should move the gates of the turbines only as fast as the column 
of water in the pipes can be accelerated or retarded. 

The foregoing does not apply to turbines set in open penstocks 
nor turbines in steel casings which have one end of their shells set 
into the dam or bulkhead, nor do these remarks apply to installa- 
tions where the conducting pipes are only a few feet long — say two 
or three times their diameter. 



PART II 

ELECTRICAL EQUIPMENT 



CHAPTER VI. 

GENERAL CONSIDERATIONS. 

The power in any electrical machine or transmission line is 
equal to the product of volts multiplied by amperes, which gives 
the number of watts. A kilo-watt (abbreviation K.W.) is equal 
to iooo watts. A horse-power is equal to 746 watts, hence a kilo- 
watt =1.34 H.P. The product of volts X amperes does not 
represent the actual power delivered by an alternating current 
system, except under certain favorable conditions, the power being 
usually less than the volts X amperes by a percentage which de- 
pends on the constants of the system. The real power is equal 
to volts X amperes X cj>, in which <j> is a factor called the power 
jactor. Only when the power factor is equal to 1 — as it is in all 
direct-current systems and in all alternating- current systems in 
which the load is non-inductive, such as incandescent lamps, 
electrolytic tanks, synchronous motors, or rotary converters — is 
the actual power equal to volts X amperes. 

The power factor of arc-lamp circuits is about 0.82, of induc- 
tion motors from 0.85 to 0.9, according to construction and size. 
The use of the power factor in calculations will be shown in later 
discussions. 

There are, in general, two systems, between which the de- 
signer of a power station may choose — namely, the alternating and 
the continuous or direct current. 

To consider the origin, interaction, and conditions of electric 

71 



72 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

and magnetic phenomena is beyond the scope and intention of this 
work. The reader who desires to pursue this portion of the sub- 
ject further, is referred to any of the many excellent treatises on 
electricity and magnetism that abound in all languages and may 
be obtained in nearly any locality. It therefore suffices to say 
here that continuous current flows always in one direction through 
an electric circuit or machine, and is the same kind of current as 
is given out by an electric battery, while alternating current flows 
first in one direction, then in the opposite direction, then reverses 
again, and continues to change its direction of flow as long as the 
electricity is produced. These reversals are very rapid and take 
place at a rate of from 50 to 250 times per second, or from 3,000 to 
15,000 per minute. If current were supplied to lamps by a battery 
and a switch were connected in the circuit so that when turned 
in one position the positive pole of the battery is connected to one 
of the wires and the negative pole to the other wire leading to the 
lamps, while if the switch be turned to another position it will 
connect the positive pole of the battery to the second wire and the 
negative pole to the first, and this switch were rapidly moved back 
and forth, the current to the lamps would be similar to the alter- 
nating current produced by alternating dynamos. Each of these 
systems has its particular place in the art and in some cases either 
is suitable for a given kind of work. 

The advantages of the direct current are as follows: Direct- 
current dynamos and motors may be obtained in a greater variety 
of speeds and sizes from standard patterns; the motors will give 
a stronger starting torque and continue to run under heavier 
overloads than will alternating-current motors; it is the only cur- 
rent which will operate storage batteries and in connection with 
them; it, only, can be used in electroplating and electrolytic 
work of a like character; its phenomena are much simpler, easily 
calculated and understood than are the laws which apply to al- 
ternating currents. It has the disadvantage, however, of requiring 
a commutator on each dynamo or motor, with brushes bearing 
against it which limits the voltage of the machines and also, when 



GENERAL CONSIDERATIONS 73 

the voltage of a direct-current system is once fixed, this also is the 
voltage of all the distribution lines and branches with their rami- 
fications and it cannot be altered except by the use of electrical 
machinery. 

The advantages of the alternating current over the direct cur- 
rent are: The dynamos and motors are simpler in their construc- 
tion and cost less than direct-current machines of similar capacity; 
the voltage may be transformed from any value to any other that 
may be desired by the use of simple and low-priced static trans- 
formers which have no moving parts and consist merely of two 
coils of wire wound on an iron core. Furthermore, in the case of 
three-phase alternating current, the amount of wire required to trans- 
mit a given power over a given distance is twenty-five per cent, less 
than the amount required for a similar direct-current transmission. 
As will be shown later, the use of high voltages is necessary when 
electrical energy is to be transmitted over long distances, and, in 
even as short a distance as one mile, the proper voltage is greater 
than that which is produced by any standard direct-current machine 
for power sendee that is made in the United States. Electric 
railways are best operated by 550 volts direct current, and the 
standard available railway equipments are all for this voltage. 
Therefore, in general, the system chosen should be direct current 
when the distance of transmission is short and the power is to be 
used on electric railways, for electrolytic work, or for supplying 
power to mills and factories where the speed of the machinery has 
to be varied through a wide range and the initial starting effort 
of the motors must be high. In cases where the conditions require 
the use of alternating current, but some direct-current is needed, 
an alternating current system should be installed and the small 
proportion of direct current needed may be obtained by using a 
rotary converter or a motor generator set, which latter is made 
up of an alternating current motor driving a direct-current dynamo. 

In every alternating-current power station there are also placed 
small direct-current dynamos, called exciters, the current from 
which is used to magnetize the field magnets of the alternating- 



74 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

current generators. In many instances the capacity of these 
exciters is made great enough to supply not only the needed field 
exciting current but to furnish some additional current for other 
purposes as well. In a power station, recently designed by the 
author, the exciters installed are large enough to furnish current 
for lighting the power station and certain adjacent buildings, in 
addition to supplying the necessary field excitation to the alter- 
nating-current dynamos. The reason for the adoption of this 
method of lighting was that the voltage of the power dynamos was 
subject to considerable variation which would have manifested 
itself by variation in the illumination if the lamps had been sup- 
plied from these machines. 

In deciding on the size and type of dynamo to be used it must 
be remembered that the lower the speed at which it runs the greater 
will be its cost for a given capacity. For this reason it is fre- 
quently cheaper to make use of a high-priced turbine which runs at 
a high speed than to purchase a lower-priced low-speed turbine 
when the machines are to be directly connected together. Thus, a 
single turbine of 500 H.P. operating under a 50 foot head will cost 
about $1,800 and will run at about 275 r.p.m. Two 250 H.P. 
turbines on a single shaft will cost $2,100 and run at 450 r.p.m. 
The cost of the 375 K.W. alternating-current dynamo, running at 
the speed of the single wheel, will cost $4,800, making the cost 
of the low-speed unit complete $6,600, while a dynamo of similar 
capacity at the higher speed will cost $3,800, making the cost of 
the high-speed unit complete $5,900, so that by using the higher- 
price turbine a lower cost generating unit is obtained. 

The size of the dynamo to be used in a power station is gen- 
erally obtained as follows: the gross horse-power to be developed 
is computed by the methods given in a previous chapter. Eighty 
per cent, of this is available at the turbine shaft. The dynamo effi- 
ciency, including the power required to operate the exciter, is about 
92 per cent. The total dynamo power, therefore, is 92 per cent, of 
80 per cent, or 73.6 per cent, of the gross available power. The 
total dynamo power thus found should be divided among several 



GENERAL CONSIDERATIONS 75 

machines, and, where possible, the number of the machines should 
not be less than four nor should the number exceed ten. When 
as many as four machines are used, if one should break down the 
other three, working at 20 to 25 per cent, overload, would deliver 
nearly the full power of the station. 

The water-wheels should each have a capacity 15 to 20 per 
cent, greater than the power required to drive its dynamo. It 
sometimes is better to drive dynamos by belts from pulleys on the 
water-wheel shaft, or in large sizes, to use rope drives, than to 
connect directly the two shafts. This is frequently true in the case 
of low heads where turbine speeds are so low that the high cost 
of the generators would make the investment for direct-connected 
units excessive. When belted units are installed, however, the 
distance required between the centres of the two shafts, in order to 
give sufficient length to the belt, increases the size of the power- 
house and likewise its cost. Before deciding, therefore, on whether 
or not it is best to use belted or direct-connected units, computa- 
tions should be made showing the comparative total cost of the 
units, plus power-house for each case. In making this computa- 
tion the item of belting should not be omitted as high-grade, double 
leather belts cost about 16 cts. per foot for each inch in width. 
Thus a 30-inch belt will cost 30 X 16 =-$4.80 per foot length, and 
with 25 feet between centres and usual size pulleys about 60 feet 
of belting are required, costing $288.00. The extra cost of the 
pulleys should also be included. 



CHAPTER VII. 
Alternating-Current Dynamos. 

There are many kinds of alternating- current dynamos, but 
at the present day the only sorts which are in general use are the 
revolving field and the inductor types. The inductor, while an 
excellent form of machine, is being almost entirely supplanted by 
the revolving-field machines, owing to the lower cost of manufac- 
ture of the latter. 

Inductor dynamos are constructed as indicated in Figs. 40 
and 41. Fig. 40 shows the complete dynamo, while Fig. 41 
shows the inductor with its central magnetizing coil. The arma- 
ture winding is placed in slots or grooves cut on the inner surface 
of the stationary ring of laminated iron which surrounds the in- 
ductor and is held in position by the external iron frame of the 
dynamo. The inductor itself consists of a wheel, having mounted 
on its rim a number of masses of laminated iron arranged in pairs, 
side by side and equally spaced around the circumference of the 
inductor wheel as indicated in Fig. 41. Encircling the rotor, 
but not in contact with it, is the circular channel carrying the mag- 
netizing coil, which corresponds to the field winding in other 
forms of dynamos. This single coil, which is stationary and does 
not rotate, magnetizes all of the rotating masses of iron on the in- 
ductor wheel. As is obvious from the figure, all of the masses of 
iron on one side of the coil are magnetized as north poles, while 
those on the other side of the coil are magnetized as south poles, 
the magnetic circuit being completed through the laminated iron 
ring encircling the inductor, which is separated from the mag- 
netized portions of the inductor by only a small air gap. There 
is no moving wire whatever in this form of dynamo and consequent- 

76 



ALTERNATING- CURRENT DYNAMOS 



77 



ly it is not necessary to use collector rings and brushes, all con- 
nections to the field and armature windings being made in the or- 
dinary manner as they are both stationary. This description and 
the figures apply of course to but one particular type, but there are 




Fig. 40. 



several forms of inductor machines which have no moving wire, and 
which work on the principles outlined above. 

Dynamos of this kind are durable, usually of high efficiency, 
and they are in every respect satisfactorily operating machines. 
Their one disadvantage is their high cost of manufacture. 

The revolving-field alternator is similar to the inductor alter- 
nator in that its armature winding is stationary, the coils being 



7 8 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



embedded in slots made in the outside ring of laminated iron. 
The rotating part consists of a wheel having fastened to its periph- 
ery a number of short field-poles, equally spaced around the 
circumference and projecting radially outward towards the en- 
circling stationary iron ring, carrying the armature winding. 
Each of these field poles is surrounded by a field winding and 
the outer ends of the poles approach very near to the inner surface 
of the stationary iron ring, a small air gap separating them. Figs. 




Fig. 41. 

42 and 43 show the stationary ring carrying the armature 
windings and the rotating field member (or rotor) respectively, 
of a standard machine of this type. The complete machine is 
shown in Fig. 44. The connections to the armature are made 
without collectors or brushes. The field-magnet windings all 
rotate and it therefore is necessary to transmit current to them 
through collector rings, having brushes bearing on them. The 



ALTERNATING- CURRENT DYNAMOS 



79 



field current, however, is always very small and the voltage low 
as compared with the output from the armature, and, therefore, 
the size of the brushes and collector rings is small, and there is no 




Fig. 42. 

difficulty whatever in their operation. This type of machine 
may be constructed at a low cost and they are so thoroughly 
satisfactory that they are almost exclusively used in the United 
States at the present time. 

Both the inductor and rotating-field machines have one ad- 
vantage in common, viz., the stationary armature winding and 
direct connection from it to the outgoing transmission line without 



8o 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



the use of collector rings and brushes. This admits of insulating 
the armature winding to the same degree that a transformer wind- 
ing may be insulated, and, in consequence, dynamos may be wound 
for extraordinarily high potentials, it being easy to obtain machines 
in many standard sizes which deliver 6,600 volts and a few have 
been made which give 13,000 volts. For comparatively short 

transmissions — say up to fifteen 
miles — these potentials are high 
enough and the use of step-up 
transformers and the expense of 
purchasing them are avoided. 

Practically all generators used 
for power transmission are for 
three-phase currents, the three- 
phase system now being standard 
for this work, as the costs of the 
generators and of the line copper 
are less than for any other sys- 
tem. There are two frequencies 
which also have become standard, 
viz., 60 cycles and 25 cycles per 
second. The higher frequency is 
suitable for supplying current to 
motors and to lamps, either incandescent or arc. It, however, 
has the disadvantage of giving a higher line drop and poorer regu- 
lation on long transmission lines than does the lower frequency, 
and, furthermore, it is difficult to operate rotary converters at 60 
cycles. Generally, the costs of transformers, dynamos, and mo- 
tors are somewhat less for the frequency of 60 cycles than for 25. 
The frequency of any dynamo is equal to the number of poles X 
revolutions per minute -r- 1 20, and conversely the number of poles 
in a machine are equal to alternations per minute -J- revolutions 
per minute or equal to cycles per second X 120 -r revolutions per 
minute. 

The lower frequency has the disadvantage of being unsuitable 




Fig. 43. 



ALTERNATING- CURRENT DYNAMOS 



8l 



for lighting, and dynamos, motors and transformers cost slightly 
more than those for 60 cycles. The inductive drop on a long 
transmission line, however, is less and rotary converters operate 
with ease at this frequency. Therefore, in choosing the frequency, 




Fig. 44. 

the character of the load is the determining factor. If the line is 
short and there is considerable lighting load and but a small 
amount of direct current is required, 60 cycles is the proper fre- 
quency. The direct current may be obtained by using small 
rotary converters which can be made to work fairly well at 60 
cycles, or by using direct-current generators driven by alternating- 
current motors. If the line is long — 60 miles or more — and a 
large amount of direct current is required at the distributing end 
of the line and the lighting load is comparatively small, 25 cycles 

6 



ALTERNATING- CURRENT DYNAMOS 83 

is the better frequency. In any case, where the larger part of the 
load is to be in the form of direct current, as for instance an elec- 
tric railway system, the low frequency should always be adopted, 
in order that rotary converters may be used and made to work 
satisfactorily in parallel. 

These factors may vary in such a manner as to render a de- 
cision somewhat difficult, and the only thing to do in such a case 
is to investigate carefully various operating plants supplying ser- 
vice somewhat similar to that contemplated in the prospective 
plant, and profit by the experience of others. 

Dynamos are made in various efficiencies, the efficiency de- 
pending somewhat on the cost. High-efficiency machines require 
more iron and copper to construct than do those of low efficiency. 
The word efficiency is used here in its technical sense and is equal 
to the power which is delivered by a dynamo divided by the power 
which must be applied to the dynamo shaft in order to obtain the 
delivered power. In a 1,000 K.W. machine the efficiency may be 
from 92 to 96 per cent. This means that from 4 to 8 per cent, of 
the total power furnished is lost in the dynamo, which loss goes 
into the form of heat, the temperature of the copper and the iron 
being raised above that of the surrounding atmosphere and a con- 
stant radiation thus produced, which dissipates a certain propor- 
tion of the total energy. Some of this lost power is also used up 
in driving the small exciter dynamo which furnishes current to the 
field magnets. The energy thus lost in a 1,000 K.W. dynamo will 
be from 40 to 80 K.W. or from 54 to 108 H.P. Whether it is 
better to pay a higher price for the dynamo of higher efficiency 
or not, depends entirely on the conditions that obtain in any par- 
ticular plant. If the water power is abundant and greater than 
will ever be used in the locality where the development is made, 
the low-efficiency machine should be used. If, however, the water 
power is limited and the value of power high, the high-efficiency 
dynamo should be installed. Taking the case of the 1,000 K.W. 
dynamo above, at the two extremes given, the salable power from 
the high-efficiency dynamo is 54 H.P. in excess of that from the 



84 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

low-efficiency machine, the water power being the same in each 
case. If this power is salable at $15.00 per annum per H.P., the 
income that may be derived from the high- efficiency dynamo is 
$810.00 per annum more than the income obtainable if the low- 
efficiency machine be used. Assuming that all increase in ex- 
penditure above that absolutely necessary to get the plant in com- 
mission must return 15 per cent, on the added investment, $5,400.00 
more could be paid for the high-efficiency machine than for the one 
having the low efficiency. The actual excess cost would not ex- 
ceed $1,000.00, so it is evident that the high-efficiency machine is 
the better paying one. This same reasoning applies also to tur- 
bines. These considerations are of great importance in every case 
where power is limited and should receive careful consideration. 

Another vital question is that of regulation. This is defined 
as the percentage change in the voltage of a dynamo between the 
limits of full-load current and no load, the field excitation and 
speed remaining unchanged. All variations in voltage at the dy- 
namo will be transmitted over the line to the points of distribution 
and, in the case of rotary converters, cause a corresponding change 
in the direct-current voltage and thereby produce fluctuations in 
the direct-current service. Also, where lights are fed from the 
line or from rotary converters the fluctuation in brilliancy with 
even small changes in the voltage are marked and the service is 
unsatisfactory. 

On the other hand, if the load be entirely of motors, a greater 
voltage change is allowable and good regulation not so necessary. 

Dynamos having high efficiency always have good regulation 
also, that is, the change in voltage with change in load is small. 

The best machines have a regulation of 6 per cent, on non- 
inductive load or 8 per cent, on an inductive load of 85 per cent, 
power factor, while some standard machines have a regulation of 
14 per cent, on non-inductive and 18 or 20 per cent, on inductive 
loads. 

The regulation of generators for long transmissions should be 
as good as possible for the reason that the drop in potential from 



ALTERNATING- CURRENT DYNAMOS 85 

the generator to the receiving motors or other translating devices 
is the sum of the drops in the generator and in the line, and both 
of these increase with increase in current. Generally, the load on 
a transmission plant, though subject to variation, does not fluctuate 
sharply, the changes in load taking place gradually, and the line 
and generator drops may be compensated for by variation in the 
generator-field excitation. Therefore, the character of the load 
influences the degree of regulation necessary, sharply fluctuating 
loads requiring a better regulation of line and generators than grad- 
ually changing loads which are subject to rheostatic control of the 
exciter. 

At present, automatic voltage regulators can be purchased in 
the open market at reasonable prices. These automatically 
adjust the field excitation to give a constant voltage at the dynamo 
terminals no matter what the inherent regulation of the machine 
itself may be. They may be adjusted to cause an increase in volt- 
age with increase in current, thereby compensating for the in- 
creased line drop, the effect being practically similar to that of an 
over-compounded direct-current dynamo. They are independ- 
ent mechanisms and may be applied to any generator and, in the 
case of dynamos of 200 K.W. and above, it is usually cheaper to 
install a dynamo having a low regulation factor, and purchase the 
voltage regulator to work with it, than to pay the higher price for 
the dynamo having a better regulation. Furthermore, the oper- 
ation of the automatically controlled dynamo is superior to that 
of one having the best possible inherent regulation and not so 
controlled. 

The speed regulation of the units may be allowed to fluctuate 
somewhat, if the voltage is automatically maintained constant, 
provided current is not furnished to any synchronous motors or 
rotary converters. Since all synchronous machinery operates 
at exactly the same electrical speed — i.e., the time of rotation from 
one pole to the next adjacent pole — as that of the generator, and 
this relation is as rigidly fixed as if the machines were geared to- 
gether, any change in generator speed must be accompanied by an 



86 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

exactly corresponding change in the speed of the synchronous 
machine. Therefore, a sudden change in the dynamo speed may 
result in the synchronous machine running out of step with the 
generator alternations, due to the fact that the fly-wheel effect of 
the rotating parts of the synchronous machines will prevent them 
from suddenly speeding up or slowing down to conform with the 
sudden changes in generator speed. As a result, the synchronous 
machines will slow down and stop and, during the period of stop- 
ping, heavy surging of current will take place on the line which, 
for the time, will destroy the regulation and may set up injurious 
voltages due to inductive or resonance effects. Therefore, the pro- 
vision for speed regulation must be very much more elaborate 
when synchronous machines are to be operated than when the 
energy is supplied only to lights and induction motors. Of 
course, gradual changes in speed do no harm if they take place 
slowly enough to allow the speed of the synchronous machines to 
follow such variations. Frequently, heavy fly-wheels are placed 
on the turbine shafts and these, when properly proportioned for the 
speed and probable maximum load changes, are effectual in pre- 
vention of sudden speed fluctuation. 

The required capacity of the dynamos depends not only on 
the power to be delivered but the character of the load. If the 
current is all used by incandescent lamps or synchronous ma- 
chines, the power factor will be approximately equal to i and the 
dynamo capacity, in kilo- watts, will be equal to the actual power 
requirement of the lamps and machines supplied, plus the loss in 
the line. If, however, the energy is supplied to induction motors 
or arc lamps, the power factor will then be considerably less than 
i, its value being usually somewhere between 0.8 and 0.9. 

The power factor may be defined, in plain words, as the ratio 
of the actual energy supplied, to the required generator capacity. 
That is, the load in kilo-watts divided by the power factor is 
equal to the required K.W. capacity of the generator. There- 
fore, if the K.W. requirement of the load is equal to 1,000 K.W. 
and the power factor is 0.8, the capacity of the generator must be 



ALTERNATING- CURRENT DYNAMOS 87 

1,000 4- 0.8, equal to 1,250 apparent K.W. If the generator 
voltage is 1,000 volts, the current — assuming a single-phase trans- 
mission — will be 1,250 amperes. The actual energy supplied, 
however, is only 1,000 K.W., and although the generator may 
apparently deliver 1,250 K.W., the actual load on the water-wheel 
is only 1,000 K. W., plus the losses in the generator. Under these 
conditions it is clear that the energy supplied is equal to the prod- 
uct of volts X amperes X power factor. The product of volts X 
amperes is called the apparent watts, and owing to the fact that the 
power factor may vary, so that the actual kilo-watts supplied by a 
given current under a given voltage may correspondingly vary, it 
has become customary to express the capacity of alternating cur- 
rent generators in kilo- volt-amperes (abbreviated K.V.A.) in- 
stead of kilo-watts. It is obvious, therefore, that where the power 
factor is 0.8, the size of the generator must be 25 per cent, greater 
than the computed load requirements would indicate, or if the 
power factor were 0.9 the generator would have to be of 11 per 
cent, greater capacity than the load demand shows. This increase 
in generator size does not require a corresponding increase in the 
power of the turbine, because with a power factor, for instance, 
of 0.8 the generator may deliver apparently 1,250 K.W. while 
the actual energy output will be only 0.8 times this or 1,000 K.W. 
In other words, a power factor requires an increase of current to 
deliver a given amount of energy and the dynamo must be large 
enough to furnish this increased current without overheating. 

When current is passed through any conductor, heat is liberated 
by an amount proportional to the resistance in ohms of the conduc- 
tor and to the square of the current in amperes, or H = I 2 R. Also 
with repeated reversals of magnetization, such as rapidly occur in 
electric generators, a certain amount of energy is absorbed propor- 
tional to the number of reversals, the mass of the iron affected, and 
the magnetic density. This absorbed energy also manifests it- 
self in the form of heat. Both of these conditions for the genera- 
tion of heat are present in every electric generator and as a result 
the temperature of a dynamo will rise above that of the surround- 



88 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

ing air until it attains a value such that it can radiate the heat as 
rapidly as it is produced. Since dynamos are made with certain 
materials in them, such as cotton and fibre, which are used for in- 
sulating purposes and which deteriorate rapidly under the in- 
fluence of high temperatures, they should be designed and pro- 
portioned so that the rise in temperature shall not be very great. 
The greater the amounts of iron and copper in a dynamo or motor 
per K.W. of output, the smaller will be the temperature rise. Other 
things being equal, the smallness of the temperature rise is a meas- 
ure of the excellence and value of the dynamo. The same factors 
in design which produce high efficiency and good regulation also 
give a small temperature rise. In fact, since the efficiency measures 
the energy lost in the generator and this energy loss is continu- 
ously dissipated in the form of heat, the efficiency practically 
measures the temperature rise, modified, of course, by certain 
characteristics of design to ventilate the heated portions. It has 
been found that about 165 F. or 74 C. is about the maxi- 
mum temperature that insulating materials will stand continuously 
without deterioration. In temperate climates it is assumed that 
the temperature of the surrounding air will rise to 90 F. or 
34 C. and on this basis the increase in temperature above 
that of the surrounding air has been fixed at 40 C. To obtain 
a smaller rise would increase the cost of the dynamo or motor by 
an amount in excess of the value which would accrue, while if 
the machine were made at a less cost for a greater temperature rise 
the insulation would deteriorate too rapidly and the efficiency be too 
much reduced to make such machines desirable at any price. The 
standard fixed, of between 35 and 40 C, is a commercial com- 
promise between ideal scientific, and practical business conditions. 
Dynamos which are to be installed in places where the tempera- 
ture of the surrounding air will be greater than 90 F. or 34 
C, such as in tropical latitudes or adjacent to boiler plants, 
must have a corresponding allowance made in the permissible 
temperature rise. Thus, if the dynamo-room is subject to a tem- 
perature of 44 C. for a prolonged period of time, the allowable 



ALTERNATING-CURRENT DYNAMOS 



8 9 



temperature rise of the dynamos should be limited to 30 C. If 
this high temperature is attained only occasionally, the tempera- 
ture rise and total temperature attained may be 5 or io° C. in 
excess of these figures. 

From these considerations it is obvious that dynamo-rooms 
should be as well ventilated and maintained as cool as possible. 

Exciting Dynamos. The small direct- current dynamos which 




Fig. 45. 

supply current to energize or " excite" the field magnets of the gen- 
erators are usually standard 125 or 250 volt machines. In small 
power stations it is usual to drive the exciter by means of a belt 
which receives its power from a pulley on the shaft of the main 
dynamo. Fig. 45 shows this arrangement. In some instances the 
exciter is mounted on the same frame with the main dynamo and its 
armature is placed on an extension of the main dynamo shaft, pro- 
ducing in effect, an exciter direct-connected to the main dynamo. 
This is shown in Fig. 46. It has the advantage of eliminating 



9° 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



the. driving belt and pulley and requiring less space for each unit. 
It, however, has the disadvantage that the small machine runs at 
the same speed as the large one to which it is connected and this, 
of course, is necessarily an extremely low speed for the small ma- 
chine.' As a result the cost of the exciter becomes abnormally 
great and its efficiency also is reduced. 

With either the belted or direct- connected exciter, each alter- 





f 






J 












v * * 




\^k ' Vfr 


!S|2§B 








£k '■ ^^*HHMw 












wilfel^^^s^,^. ft . p 




^BE^ 















Fig. 46. 

nator is provided with its individual exciter. In the larger power 
stations it is customary to install only two exciters regardless 
of the number of alternating-current generators. Each of these 
machines is driven by its own turbine to which it usually is direct- 
connected except when the head on the water-wheels is too low to 
obtain a turbine speed corresponding to the excrter speed. The 
sizes of the exciters and their driving turbines are such that either 
exciter will furnish sufficient current to energize the field magnets 



ALTERNATING- CURRENT DYNAMOS 



9 1 



of all the generators in the station. Only one exciter is operated, 
the other being held in reserve as a spare in case of accident. 

Fig. 47 shows the usual connections between the exciters and 
generator fields. Ei and E2 are exciter armatures connected to 
the bus-bars Li, L2, by switches Si, S2 respectively, ri, r2 are 
rheostats in the exciter fields to adjust their voltages. Fi and F2 
are the generator fields connected to the bus-bars by the field 
switches FSi and FS2. Rheostats Ri and R2 are inserted in the 
generator-field circuits so that the excitation of these fields may be 
adjusted independently of each other. When each generator is pro- 




Fig. 47. 

vided with its own separate exciter, the excitation of the generator 
field is varied by adjusting the exciter-field rheostat so that the exciter 
armature gives just the required voltage to produce the desired field 
excitation, the resistance of the main dynamo rheostat being prac- 
tically all cut out, thus minimizing the energy loss from the exciter. 

As explained in discussing temperature rise of the main dyna- 
mos, the capacity of exciters should be such that they will never 
attain a temperature above 74 C. 

The exciting current required by any alternating- current genera- 
tor should not vary greatly with change in load on the generator. 
It is usual to specify that the required field excitation at full load 
with 80 per cent, power factor shall not be more than 20 per cent, 
in excess of that required to produce the same voltage at zero load, 
the speed of the generator being the same under both conditions. 

The proper voltage of generators is fixed by the transmission 
conditions which are discussed in chapter IX. 



CHAPTER VIII. 

Transformers. 

As will be presently set forth under the subject " Transmission 
Lines," high voltages are essential on long-distance lines for com- 
mercial reasons. Generally, where the pressures exceed 6,600 
volts it is not expedient to produce it directly in the generator wind- 
ings, and transformers are used which receive the generator cur- 
rent at some low voltage and transform it into practically the same 
amount of electrical energy of less current at much greater voltage. 
When so used they are termed "step-up" transformers. The 
generator voltage when step-up transformers are used may be 
anything desired, as the cost of transformers is dependent only 
on their K.W. capacity and the voltage of the high-tension side. 
It is usual, therefore, to install generators that give 1,000 to 2,000 
volts, where step-up transformers are used to produce the necessary 
line pressure, and in many cases 440 volt generators are adopted. 
It is better to use low-voltage dynamos in connection with step-up 
transformers, as they are less dangerous, there is less liability to 
break-down due to failure of insulation, and the switchboard equip- 
ment is reduced in cost, except in cases where the kilo-watt capacity 
of the plant is so great that the currents at the lower voltage be- 
come extremely large, in which event the excessive size of the 
switches and instruments and the panels on which they are mount- 
ed makes the cost of the switchboard equipment higher than it 
would be for smaller devices constructed to work under greater 
pressures. 

The high tensions used for transmission are not suitable nor ap- 
plicable to motors, lamps, or other translating devices, and it there- 
fore is necessary to reduce the voltage at the receiving end of the 

92 



TRANSFORMERS 93 

transmission line, which reduction is effected by means of trans- 
formers similar to the step-up transformers. Where they are used 
for voltage reduction they are called " step-down" transformers. 

The transformers at the power station are usually located in 
an extension of the dynamo-room. When they are small, say not 
above ioo K.W. in size, they are placed in rows in the extension 
provided for them, with ample space around each one so that it 
may be inspected from every side. In the case of large transform- 
ers, the best practice requires that a separate brick or concrete 
chamber be constructed for each transformer, with a door of iron 
on the front of each chamber, made to slide or to roll out of place 
so that the clear opening obtained when the door is moved is equal 
practically to the area of one side of the chamber. In practice 
the construction adopted is to make a long room of comparatively 
small height and depth and separated into a number of compart- 
ments by means of concrete or masonry division walls, each com- 
partment being a fire-proof containing-chamber into which a 
single transformer may be placed. This arrangement is particu- 
larly necessary in the case of oil-cooled transformers, as there is 
danger of conflagration at times when sudden arcs occur due to 
break-down of insulation which sometimes takes place. These 
fire-proof chambers add but little to the cost of a power-house and 
should always be installed when practicable. They give the 
additional advantage of preventing the attendants from coming 
in contact with the high-tension terminals or receiving dangerous 
shocks from static discharges which sometimes occur. 

In order to render the transformers accessible for inspection 
and repair, they are usually mounted on an iron frame having small 
rollers under them, so that any one may be rolled out of its com- 
partment with ease and quickness. Many stations have the floor 
level of the transformer chambers about twenty inches above the 
floor level of the station itself, with a track running along in front 
of the row of compartments. A small car, having its platform on a 
level with the floor of the compartments, runs on this track, and 
with this arrangement any transformer may be rolled out onto the 



94 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

car and conveyed to the repair-room or any other place provided 
for inspection and repair of these devices. This is a somewhat 
elaborate construction and suitable only for the larger power- 
houses of 6,000 K.W. or more. 

Some engineers prefer to construct a separate building for the 
transformers, a short distance from the generating station. This 
is by no means a necessary plan, however, and its general adoption 
is not to be advised, though certain peculiar conditions may some- 
times make it desirable. 

Transformers being simply special forms of electric generators 
in which the lines of forces are cut by varying the magnetic flux 
instead of mechanical rotation, they are subject to the same laws 
and commercial considerations as are the dynamos in the power 
plant. They are subject to temperature rise, and in order to cut 
down their cost for a given output it is customary to employ some 
means of artificially cooling them, when they reach a size of 100 
K.W. or more. 

The methods of cooling in general use are: (1) by an air blast 
from a blower; (2) by filling the transformer case with oil which 
is circulated through pipes that are surrounded by water which ab- 
stracts the heat from the oil, thus maintaining the temperature in 
the case at a safely moderate value; and (3) by arranging a coil 
of pipe inside the transformer case, the case being filled with oil, 
and circulating water through the pipe coil and thereby abstracting 
the heat from the oil. Fig. 48 shows the last-named type with 
the casing removed. The coil of pipe for the circulation of cooling 
water is clearly shown. 

The air-blast transformers are generally used in the sub-stations 
at the end of the line, while the oil-filled transformers, cooled by a 
coil of water-filled pipe inside the casing, are used at the power 
station for raising the transmission voltage, it being usually the case 
that plenty of water for cooling purposes is available at the power 
station, while little or none is obtainable at the sub-station unless 
purchased from a water-supply company at prohibitive rates. 

At the power station, the cost of maintaining the water cir- 



TRANSFORMERS 



95 



culation is nil, as the head on the water-wheels will also force water 
through the cooling coils. When the transformers are placed 
above the level of the head water, a siphon arrangement can be 




Fig. 48. 

used if the maximum lift of the water is not over ten feet above the 
level of the head water and the head itself is twenty feet or more. 

The oil in the transformer case acts also as an insulator pre- 
venting break-downs and re-insulating any puncture that may 
occur due to abnormal voltages from surges on the line. It also 
prolongs the life of the insulating materials used in the construc- 
tion of the coils, so that its value is twofold. 



96 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

As in the case of generators, transformers have a certain effi- 
ciency and regulation and these are dependent on the amounts of 
copper and iron used in their construction and, therefore, on the cost". 

Good transformers have efficiencies ranging from 96 to 98 
per cent., depending on the size and design. The regulation is 
from 3 to 7 per cent. The desirable efficiency is a commercial 
question and determined in the same manner that the efficiency 
of the generators is fixed. The regulation is also settled by the 
same considerations which govern the selection of the generator 
regulation. 

This latter, however, is not a serious matter if automatic volt- 
age regulators be used. 

The capacity of the transformers is determined by the method 
of computation given in chapter IX. In three-phase systems any 
number of generators may be used, all working in parallel and all 
delivering their power to one set of bus-bars. From these bus- 
bars, the power passes to the transformers which are also con- 
nected in parallel to a set of high-tension bus-bars which latter 
supply current to the transmission line. With this arrangement, 
it is evident that the number of transformers necessary bears no re- 
lation to the number of generators. For 3-phase systems the 
number of transformers must be divisible by three, however, as 
there are three high-tension bus-bars to deliver current to three 
outgoing transmission wires. 

Many engineers prefer to install three transformers for each 
generator, with switching arrangements for connecting any three 
transformers to any one of the generators direct, and putting the 
high- voltage windings of the transformers, only, in parallel. There 
is no good reason for this practice and there are several reasons 
against it. A given capacity costs less in a few large-size trans- 
formers than it does in a larger number of smaller sizes and, also, 
each transformer is a possible source of trouble and it is not good 
practice to multiply any such possibilities. Large transformers 
have a slightly higher efficiency for the same character or con- 
struction than smaller ones. 



TRANSFORMERS 



97 



Transformers should be well protected against lightning, as 
they receive any discharge that reaches the station. They should 
always have their cases well grounded, so that there can never be 
any dangerous potential between the case and the earth to imperil 
the lives of the attendants. Recent practice seems to favor con- 
necting the secondary windings to earth, so that in case of a break- 
down of the insulation between the high-tension and low-tension 
windings, no high voltage can be maintained between the low- 
tension winding and the earth. 

There are three general methods of connecting transformers 
for three-phase circuits; namely, Y connection, A or mesh con- 
nection, and resultant mesh connection. The first two methods re- 
quire three transformers or a number which are connected in three 
parallel groups, while the third method requires only two transform- 
ers or a number which are connected to form two parallel groups. 

The Y connection is shown in Fig. 49. 
the primary windings of trans- 
formers 1, 2 and 3, respectively, 
T x T 2 T 3 , the three wires of the 



P x P P 3 represent 



Pi 

/www 



A/WWV 



/WWvW 



Si 




s 2 


i 1 


S3 

> 




Di 




D 2 





incoming transmission line, Si S 2 
S 3 the secondary windings of the 
three transformers, and D x D 2 D 3 
the wires of the distribution cir- 
cuit. As is clear from the figure, 
a high-tension wire is connected 
to one side of each primary wind- 
ing of each transformer, the other 
three terminals of the windings 

being joined together. Similarly, the three secondary windings 
have each a terminal connected to one of the distribution wires, 
while the other three terminals are joined together. 

The A or mesh connection is as shown in Fig. 50. One ter- 
minal of the primary P x is joined to a terminal of P 2 , the other side 
of P 2 being connected to a terminal of P 3 , while the remaining ter- 
minals of Pi and P 3 are joined together. The three transmission 



Fig. 49. 



9 8 



DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



wires T 1 T 2 and T 3 connect to the three junctions between the coils 
as indicated. The connections of the secondary coils to the three 



9- 



p p 

IV\AAAA^_X_VWWvO--^^ 




s; 



^X>^— 




Fig. 50. 

distributing wires are made in a similar manner and are obvious 
from the figure. 

The resultant mesh connection, made with two transformers 
is depicted in Fig. 51. The two primary coils of the two trans- 
formers are connected together on one side as shown, while the 
other two sides are connected to the transmission wires T x and T 3 . 

T 2 is connected to the common 
junction point between the two 
primary coils P t and P 2 . The 
connections on the low- tension 
or distribution side are exactly 
similar and easily followed from 
the diagram. 

Each of these methods of 
connecting transformers has cer- 
tain advantages, and the selection 
between the Y and the A seems 
to be largely a matter of personal 
preference rather than any real superiority. The resultant mesh 



K/WWW 



yvwwvx 



Si 



AVV\ 



TRANSFORMERS 99 

is not suitable for large powers and has its field of usefulness 
limited to supplying current to small motors, acting as a step-down 
transforming system. 

In general, transformers for a given capacity and voltage are 
slightly cheaper and smaller when connected in Y fashion than 
when connected in mesh. On the other hand, the mesh connec- 
tion has the advantage that if one of three transformers should 
break down it may be cut out and the operation of the plant would 
not be interrupted, the remaining two transformers working as 
resultant mesh-connected units. The two can, of course, deliver 
only about sixty-six per cent, of the required energy if they work at 
their normal rating, but by overloading them fifty per cent, and at 
the same time increasing to the highest possible amount the cir- 
culation of the cooling medium — whether air or water — the full 
load may probably be carried for one or two hours without injury 
to the overloaded transformers. For this reason the majority of 
plants have adopted the mesh connection. 

A spare transformer should be kept in every power station 
ready to connect quickly in case of accident to any one of the 
operating transformers, and where they are all mounted on rollers, 
the removal of an injured transformer and the substitution of a 
spare one is accomplished expeditiously. 



CHAPTER IX. 

Transmission Conductors. 

Transmission lines from the power station to the point of dis- 
tribution, or to the town limits of a city, are always of bare un- 
insulated wire. Copper is generally employed, though aluminum 
is occasionally used. 

The electrical problems which are involved comprise : (i) the 
determination of the sizes of wires and their relative positions to 
carry a given amount of energy over the distance from power 
station to point of distribution with a specified loss in energy; 
(2) the calculation of the necessary voltage at the power station to 
produce the required voltage at the receiving end of the line; (3) 
the computation of the energy required at the dynamo to deliver 
the given energy at the receiving end of the line ; (4) the calculation 
of the sizes of dynamos and transformers necessary to deliver the 
specified energy; and (5) the protection of the line against lightning 
discharges. The mechanical problems are: (1) the method of 
supporting the wires on insulators; (2) the strains in wires, poles, 
pins, cross arms, and insulators which are allowable ; (3) the proper 
organization of the pole line. 

Taking up first the electrical problems, the examples given later 
show the methods employed to compute the first four mentioned. 

Standard wires. — Wires are given arbitrary gauge numbers, a 
certain diameter and area corresponding to a given gauge num- 
ber. In electrical computations the circular mil is the unit gener- 
ally used. The number of circular mils (abbreviation, cir. mil) 
in a wire is equal to 1,000 times the diameter in inches squared. 
Thus a wire 0.25 inch in diameter has an area of (0.25 X iooo) 2 
= 62,500 circular mils. The actual area of a wire, in square in- 
ches, is equal to cir. mils X 0.7854 -f- 1,000,000. The following 

100 



TRANSMISSION CONDUCTORS 



IOI 



wire table gives the gauge numbers of various sizes of copper 
wire, the diameter in inches, the number of cir. mils in each, the 
resistance in ohms per 1,000 feet, and the weight in pounds per 
i, ooo feet and per mile of soft-drawn copper: 



Bare Copper Wire. 
Dimensions and Weights. 



B. & S. 
gauge. 


Circular 
mils. 


Diameter, 
mils. 


Pounds 
per 1,000 ft. 


Pounds 
per mile. ■ 


OOOO 

ooo 

oo 

o 


211,600.00 
167,802.93 

l33>°79-°4 

105,534-02 


460.000 
409 . 640 
364.800 
324.860 


639-33 
507.01 
402.09 
318.86 


3,375-66 

2,677.01 
2,123.03 
1,683.58 


i 

2 

3 
4 


83,694.49 
66,373.22 

52,633.54 
41,742.58 


289.300 
257.630 
229.420 
204.310 


252.88 
200.54 

I 59-°3 
126.12 


i,335- 21 
1,058.85 

839.68 

665.91 


5 
6 

7 


33,102.16 
26,250.48 
20,816.72 


181.940 
162.020 
144.280 


100.01 

79-32 
62.90 


528.05 
418.81 
33 2 - 11 



Bare Copper Wire. 
Resistance Calculated at 70 F. 



Ohms per 
1,000 ft. 


Ohms per 
1,000 ft. 


Ohms per 
mile. 


Feet per 
ohm. 


Ohms per 
pound. 


oooo 

000 

00 




0-04893 
0.06170 
O.07780 
O.09811 


0.2621 

0-3306 
O.4168 

0-525 1 


20,147 

J 5,97 2 
12,668 

10,055 


0.0000776 
0.0001234 
0.0001962 
0.0003114 


1 
2 

3 
4 


0.1233 
0.1560 
0.1967 
0.2500 


O.6627 
0.8360 

I-054 
1.329 


7,968 
6,316 

5,010 
3,974 


0.0004960 
0.0007894 
0.001254 
0.001994 


5 
6 

7 


0.3124 
O . 4000 
0-5044 


1.676 
2. 113 
2.663 


3,i5o 

2,499 
1,982 


0.003173 
0-005043 
0.008013 



Hard-drawn copper wire is frequently used where the spans 
are particularly long, because of its greater tensile strength. The 



102 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

strength of soft-drawn copper is about 30,000 lbs. per square inch, 
while hard-drawn copper has a strength of double this, or 60,000 
lbs. per square inch. The resistance of hard-drawn copper is 
about 5 per cent, greater than that of soft-drawn, and this percentage 
should be added to the tabular resistances as given, when hard- 
drawn copper is to be used. 

To compute the size 0} wire for a direct-current transmission 
line, the allowable loss in the line must be assumed. The current 
in the line will be equal to the kilo-watts X 1,000 divided by the 

_ K.W. X 1,000 

voltage, or 1 = . The size of wire required is equal 

K 

2 X D X I X 11 . . , ., t • , 

to in circular mils. I is the current, in amperes, 

EXp 

D is the distance of transmission in feet, E is the voltage at the re- 
ceiving end of the line, p is the loss allowed. The energy loss in 
a circuit is equal always to the resistance X (current) 2 , or, loss = 
PR. As an example, assume a 2 -mile transmission ( = 2 X 5,280 
= 10,560 feet), 250 K.W. to be delivered, the voltage at the receiv- 
ing end to be 520 volts and the loss to be 10 per cent. Current = 

250 X 1000 . 2 X 10,560 X 482 X 11 

=482 amp. cir. mils. = = 2,- 

520 520 X 0.10 

150,000 cir. mils. 

This nearly corresponds to 10 wires No. 0000 size as given 

in the table. The total weight per 1,000 feet is 640.5 X 10= 6,405 

lbs. The total length of wire is twice the distance of transmission = 

2 X 10,560 = 21,120 ft. Total weight of wire = 2i,i2o X 6,405 -f- 

1,000 = 135,000 lbs. Add 3 per cent, for sag and joints = 135,000 + 

4,050 = 139,050 lbs. The resistance of the circuit is one-tenth the 

resistance of a single circuit of No. 0000, there being ten wires in 

parallel. The resistance of a No. 0000 wire is about 0.05 ohm 

per 1,000 ft., and the resistance of a complete circuit of this 

size wire is, for this distance of transmission, 21,120 X 0.05 = 

1.056 ohms. Resistance of 10 wires in parallel =1.056. ■*■ 10 

= 0.1056 ohm. 



TRANSMISSION CONDUCTORS 



103 



Voltage drop in the line = amperes X ohms = 482 X 0.1056 = 
51 volts. 

Voltage at the generator = volts at receiving end + volts drop = 
520 + 51 = 571 volts. Actual loss = I 2 X R= (482 ) 2 X 0.105 = 



24,500 watts = 24. 5 K.W. Per cent, less 



24.5 



250 



= 9.82 per cent. 



If the K.W. capacity, the transmission distance, and the per- 
centage loss be the same as before, but the voltage at the receiving 
end is 1,040 volts, or double the previously assumed value, the 
amount of copper required will be greatly reduced. 

250 X 1,000 



Current = 



1,040 



240.5 amps. 



_. ._ 2 X 10.560 X 240.5. X 11 

Cir. mils. = = 537.500. 

1,040 X 0.10 

Compared with the cir. mils required for the previous case it is 
seen that this is just one-fourth the amount computed for a 520- 
volt pressure. As a matter of fact, the amount of copper re- 
quired is inversely as the square of the voltage of transmission. 
This is the reason for the employment of high voltages on long 
transmission lines. 

In very short lines the size of wire may be fixed, not by the drop 
in the line, but by the current-carry- 
ing capacity of the wire. A given 
size of wire can carry only a certain 
current, regardless of the drop or loss. 
The adjoining table gives the maxi- 
mum currents allowable in various- 
size bare wires, to Brown and Sharpe 
gauge. 

In alternating-current transmission 
lines there is an inductive drop as well 
as the drop due to the resistance. 
This makes the total line drop greater than in the case of direct or 
continuous currents. The energy loss, however, is only that due 



Size of 


Allowable 


wire. 


current. 


0000 


400 amps. 


000 


320 




00 


270 




O 


240 




I 
2 


190 
160 




3 


135 




4 


115 




5 
6 


92 

80 





104 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

to the product of the square of the current flow and the resistance 
of the line, and is not equal to the drop multiplied by the current. 

Take as an example a single-phase transmission of 750 K.W. 
to be delivered at the receiving end; voltage 10,000 volts; dis- 
tance 14 miles; energy loss 10 per cent.; power factor 0.85; fre- 
quency 25 cycles per second; wires of circuit 36 inches apart; 
step-up and step-down transformers used having efficiencies of 
97 per cent. 

The apparent kilo- watts or K.V.A., delivered at the receiving 

750 
end will be the actual K.W. divided by the power factor = = 

882.3 K.V.A. 

750 

Actual energy delivered to the step-down transformers — 

0.97 

= 773 K.W. 

773 
Apparent K.W. delivered to step-down transformers = = 

0.85 

910 K.V.A. , which is the apparent energy transmitted over the 

line. 

910 X 1,000 

Current in the circuit = =91 amps. Loss is to 

10,000 

be 10 per cent, of the delivered energy = 75 K.W. = 75,000 watts. 

Loss in watts also equals I 2 xR=(9i) 2 XR. 

7 5X1,0 00 

(9i) 2 
The resistance per 1,000 feet is equal to the total resistance as 

found above, divided by the number of thousands of feet in the 
complete circuit, which is equal to twice the transmission dis- 
tance, there being two wires to each circuit. 

9.07 9.07 

Res. per 1,000 feet = '- 1,000= =0.0613 

F 2 X 14 X 5,280 148 

ohm. 

From the table, this corresponds most nearly to No. 000 wire, 

which should be adopted. The actual resistance of No. 000 



(9i) 2 XR = 75 K.W., R= -^— = 9.08 ohms. 



TRANSMISSION CONDUCTORS 



105 



is 0.0617 per 1,000 feet, which makes the resistance of the circuit = 
148 X 0.0617 = 9.14 ohms, 148 being the length of the circuit in 
thousands of feet. The volts drop due to resistance will be equal 
to the current X the resistance = 91 X 9.14 = 831 volts. 

To find the volts drop due to reactance consult the table fol- 
lowing : 



Distance Apart of Conductors.* 



Size of 
Wire 


Twelve 
inches 


Eighteen 
inches 


Twenty-four 
inches 


Thirty 
inches 


Thirty- six 
inches 


0000 


-193 


.212 


.225 


-235 


.244 


000 


.199 


.217 


.230 


.241 


.249 


00 


.204 


.222 


.236 


.246 


-254 




1 


.209 
.214 


.228 
- 2 33 


.241 
.246 


.251 
.256 


-259 
-265 


2 


.220 


.238 


.252 


.262 


.270 


3 


.225 


.244 


-257 


.267 


-275 


4 

5 
6 


.230 
.236 
.241 


.249 

-254 
.260 


.262 
.268 
.272 


.272 
.278 
.283 


.281 
.286 
.291 



* Reactance volts in 1,000 feet of line ( = 2,000 feet of wire) for one ampere at 7,200 alter- 
nations per minute (60 cycles per second) for the distance given between centres of 
conductors. 

The values given in this table are for frequencies of 60 cycles per 

second. To find the factor for other frequencies, multiply the 

factor in the table by the frequency, and divide the product by 60. 

The result will be the reactance factor for the desired frequency. 

From the table the reactance volts per 1 ,000 feet of transmission 

distance ( = 2,000 feet of circuit) for No. 000 wires placed 36 inches 

apart is 0.249 volt for each ampere flowing when the frequency 

is 60 cycles per second. Therefore, the reactance volts for the case 

under consideration and basis of 60 cycles would be (14 X 5,280 -s- 

1,000) X 91 X 0.249 = 74 X 91 X 0.249 = 1,678 volts. The factor 

0.249 i s > however, for a frequency of 60 cycles, and the frequency 

of the system under discussion is 25 cycles. Therefore the above 

value must be changed to one proportional to the frequency, and 

1,678 X 25 

the actual volts will be, ■ = 700 volts. 

60 



Io6 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

The line drop is equal to the square root of the sum of the 
resistance drop squared and th e reactance volts squared, or drop = 
V(res. volts) 2 + (react, volts) 2 = V(83i) 2 + (7oo) 2 = i, 086 volts. 

The energy loss = I 2 R=(c;i) 2 X 9.14 = 75.8 K.W. = 10.1 per 
cent, of the delivered power. 

Apparent energy loss in line = volts drop X line current = 1,086 
X 91 =98.8 K.V.A. 

Actual energy to be delivered by the step-up transformers is 
that delivered to the step-down transformers + loss in the line = 
773 K.W. + 75.8 K.W. = 848.8 K.W. 

The apparent energy delivered by the step-up transformers 
is equal to the apparent energy delivered to the step-down trans- 
formers + apparent energy lost in the line = 910 -|- 98.8 = 1,008.8 
K.V.A. 

Actual energy delivered to the step-up transformers is equal 

to their output divided by their efficiency — 97 per cent, in this case : 

_ 848.8 

Energy = =875 K.W., which is the actual energy the dynamo 

°-97 

must deliver to the step-up transformers. 

The apparent energy delivered to the step-up transformers is 

equal to the apparent energy delivered by them to the line, divi- 

1,008.8 

ded by the transformer efficiency = = 1,040 K.V.A., which 

0.97 

is the required dynamo capacity. 

The computations, then, summarized, are as follows: 

Size of generating equipment 1,040 K. V. A. 

Size of step-up transformers 1,008.8 K. V. A. 

Size of step-down transformers 910 K. V. A. 

Size of line wire, No. 000 B. & S. gauge. 

Total losses in system from generator to motors = 

8 75~ 75° I2 5 K. W. 

Current in line 91 amps. 

Voltage of step-up transformer =10,000 + 1,086 = 11,086 volts. 
The power required at the turbine shaft, if the dynamo em- 



TRANSMISSION CONDUCTORS 107 

ciency is 94 per cent, will be equal to the actual energy deliv- 
ered by the dynamo divided by its efficiency. This is equal to 

875 
— = 831 K.W.= 1,246 H.P. 

0.94 

The size of the turbine should be increased by about 20 per 

cent, to take care of speed regulation and wear. This would make 

the turbine power 1,506 H.P. If the efficiency of the turbine is 

80 per cent., the gross hydraulic power necessary to deliver the 750 

1,246 

K.W. at the motors is = 1,557 H.P. 

.80 

The plant would be divided into three units. Each turbine 
would have a capacity of 500 H.P., making the aggregate 1,500 
H.P. Each dynamo would give 350 K.V.A., making 1,050 K.V.A. 
total. There would be four transformers at the power station of 
250 K.V.A. each, giving a station-transformer capacity of 1,000 
K.V.A. The receiving transformers would be three in number, 
each of 300 K.V.A. capacity, making a total of 900 K.V.A., all of 
which figures correspond very closely to the actual computed re- 
quirements and which are obtained with standard apparatus. 

The usual transmission is three-phase, a circuit being made 
up of three wires of equal size and resistance. There are two 
methods of computation which may be followed. One is to divide 
the delivered energy by 2, and assume a single-phase system 
supplying this half the total energy. On this basis, compute the 
size of wire, the resistance drop, the reactance drop, and total drop 
as given in preceding example. Each of the three wires of the 
three-phase circuit will then be the same size as that computed, and 
the drop will be the same. The more complete method, is, how- 
ever, fully indicated in the following example: 

Assume a three-phase system to deliver 8,000 K.W. to a 
distribution circuit fed from a high-tension transmission line. 
Power factor of the distribution circuit = 0.88; voltage of trans- 
mission at receiving end = 25,000 volts; distance 35 miles ( = 
184,500 feet); frequency 25 cycles; energy loss in transmission 
line 8 per cent, of delivered power; dynamo efficiency 95 per cent.; 



108 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

transformer efficiency 97 per cent.; wires 24 inches apart, ar- 
ranged in triangular relationship (see Fig. 52). 

Actual energy delivered by step-down transformer = 8,000 K.W. 

A , 8,000 

Apparent energy = actual -*- power factor = - = 909iK.V.A. 

0.88 

T. . , 8,000 

Energy input to step-down transformers = = 8,247 K.W. 

0.97 

actual. 

A . 8,247 8,247 

Apparent energy input = = - = 9,361 K.V.A. 

power factor 0.88 

Energy loss in line = 8 per cent, of 8,000 K.W. = 640 K.W. 
The actual energy transmitted over the line per wire is one-third 

8,247 

of the total = = 2,749 K.W. 

3 

9,361 
The apparent energv transmitted over the line per wire is 

3 

= 3,120 K.V.A. 

In any three-phase system the effective voltage is equal to the 
line voltage divided by V 3 or 1.732. 

25,000 
The effective voltage, therefore, of this system is 

i-73 2 

= 14,400 volts. The line current per wire = apparent energy 
per wire delivered to the step-down transformers divided by the 

3,120 X 1,000 

effective volts, which for this case = = 217 amperes. 

14.400 

640 
I 2 R = line loss = 64o K.W. total and per phase= — =213.3 

3 

K.W. 

213.3 X i>ooo 213.3 X 1,000 

R = = = 4-^4 ohms. 

I 2 (217) 2 4 ^ 

This is the total resistance of one wire, which in computing three- 
phase lines is the length always taken instead of double the 
length of transmission. This assumption of the single distance is 



TRANSMISSION CONDUCTORS 109 

compensated for by reducing the line voltage in the calculations 

in the ratio of 1 to 1.732. 

Length of the single wire = 184,500 feet. 

4.54 

Resistance of wire per 1,000 ft. = = 0.0246 ohm. 

184.5 

This resistance is less than that of a No. 0000 wire, and con- 
sequently should be divided into two separate circuits at least. 
The current per wire will thus be halved, and the resistance per 
wire correspondingly increased. 

For two circuits: 

217 
I = — = 108.5 amperes per wire. 

213.3 K.W. 

I 2 R= = 106.6 K.W. per wire. 

2 

106.6 X 10,000 

R = =0.08 ohms per wire. 

(108.5) 2 

_ . . 9.08 

Resistance per 1,000 feet of wire = =0.0492. This cor- 

184.5 

responds most nearly to a No. 0000 wire. Adopting this, the re- 
sistance per 1 ,000 feet of wire is 0.04893 and its total resistance is 
0.04893 X 184.5 = 9 ohms. 

Energy loss per wire = I 2 R= (108.5) 2 X 9 = 106.000 watts. 

Energy loss per circuit = 3 X 106 = 318 K.W. 

Energy loss both circuits = 2 X 318 = 636 K.W. 

Resistance drop per wire = I R = 108.5 x 9 = 9?6 volts. 

Reactance volts, computed by factor from table as follows: 

Reactance volts per 1,000 feet of transmission distance for each 
ampere of current in a wire No. 0000 size, with a separation of 24 
inches and a frequency of 60 cycles is, from the table, 0.225. 

Reactance volts per 1,000 ft. for 108.5 amperes = 108.5 X 

0.225 = 24.2 volts. Reactance volts for 184.500 ft. = 184.5 x 

4,460 

24.2 = 4,460 volts. Reactance volts for 25 cycles = X 25 = 

60 

1,860 volts. 



IIO DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

This value is for a double circuit, and in calculating a three- 
phase transmission only one leg is considered. Obviously, the re- 
actance volts are half the amount per leg of the reactance volts for 

i, 860 

a double circuit. Hence reactance volts, actual will be = 930 

2 

volts. 

Volts drop = V (Resistance drop) 2 + (Reactance volts) 2 ; 

in this case = V (976)* + (930^ = 1,272 volts. 

Apparent energy lost in line = 1,272 X 108.5 = 138 K.V.A. per 
wire. Total for the six wires of the two circuits is equal to 6 X 138 
= 828 K.V.A. 

Actual energy delivered by the step-up transformers to the line 
= actual energy delivered to step-down transformers + line loss 
= 8,247 + 636 = 8,883 K.W. 

Apparent energy delivered by step-up transformers is the ap- 
parent energy delivered to the step-down transformers + appar- 
ent energy of the line = 9,361 + 828 = 10,189 K.V.A. 

Actual energy delivered to step-up transformers = energy given 

8,883 

out by them divided by their efficiency = =9,100 K.W. 

0.97 

The apparent energy input to the step-up transformers = 

apparent energy delivered by them divided by their efficiency = 

10,180 

-^ = 10,500 K.V.A. 
0.97 

This last is, of course, the apparent energy supplied by the 
generators and must be the generating capacity, while the actual 
energy delivered by the generators is 9,100 K.W. 

Summarizing the computations; 

Size of generating equipment 10,500 K.V.A. 

Size of step-up transformers 10,189 K.V.A. 

Size of step-down transformers 9,091 K.V.A. 

Line wire — two circuits of three wires each, 

size B. & S. gauge No. 0000 



TRANSMISSION CONDUCTORS III 

Total loss in system from generator to 

motors = 9,100 — 8,000 1,100 K.W. 

Current in each wire 108.5 amps. 

Effective voltage of step-up transformers = 14,400 + 1,272 = 
15,672. 

Voltage between wires at step-up transformers = 15,672 X 
1.732 = 27,200. • 

If two pole lines each carrying two circuits were run, the load 
would thus be divided among four circuits, and the size of each 
wire would be halved. The resistance drop would be the same, 
but the reactance drop would be diminished about half because 
only half the current, as before computed, would flow in each line, 
and the calculations show that the amount of the reactance volts 
depends on the current flow. Also, a wire as large as No. 0000 
is heavy and difficult to erect. Therefore, for this and other prac- 
tical reasons that make desirable a double pole line, it would be 
better to run four circuits, two on each pole line. 

The turbine power required is based on the actual energy — 
9,100 K.W. — delivered by the dynamo, and is computed exactly 
as in the preceding example. 

When step-up transformers are omitted, the calculation is some- 
what simplified. The use of these transformers is a question which 
must be settled for each case. Their advantages are : the use of a 
low- tension dynamo, the use of low- voltage switching and manipu- 
lating apparatus, confining the high-voltage currents in an iron 
case filled with insulating oil, and decreased cost of line copper. 
Their disadvantages are : initial cost, the addition of a weak point in 
the circuit, and the continual power loss which attends their opera- 
tion. 

Frequently, it is better to use a 6,600-volt generator, omit the 
transformers, and with the money thus saved add to the quantity 
of copper or even spend a little more for the wire. It is better 
to invest money in a staple commodity like copper, which does 
not depreciate and always has a market value, than to invest 



112 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

in electrical apparatus, when the differences in initial cost and 
operating losses are slight. The question of the transmission 
system is more a financial than an electrical problem, and must be 
solved on the former basis. 

The foregoing calculations may be summarized in formulas 
as follows: 

Let E = voltage at receiving end between wires. 
" E = voltage at station end between wires. 
" I = current in line. 
" F = power factor. 
" D = distance of transmission in thousands of feet = (dist. 

in miles X 5,280 -s- 1,000). 
" N=frequency of system in cycles per second. 

M = efficiency of step-down transformers. 
" M t = efficiency of step-up transformers. 

P = percentage energy loss in the line h- 100, referred to 

delivered power. 
R = resistance of each wire of a circuit per 1,000 feet. 
" S = reactance volts in line. 
" K.W. = actual energy delivered. 

Then for a single-phase system: 

K.W. 
Energy to step-down transformers = (1) 

K.W. 
Apparent energy to step-down transformers = (2) 

K.W. X 1,000 
1 = (3) 

M X F X E dJ 

K.W. X 1,000 X P . , 

R = (in ohms per 1 ,000 feet of wire) (4) 

2 X D X P 

Resistance drop = 1 X R X 2D (5) 

QXIXDXN 
Reactance drop = (6) 

60 

Q being the factor from the table for the size of wire adopted 
and the distance of separation between wires. 



a 



a 



TRANSMISSION CONDUCTORS 113 

Line drop = V (resist, drop) 2 + (react, drop) 2 (7) 

Energy delivered in K.W. by step-up transformers 

K.W. 
= — — + I 2 X R X 2D (8) 

M v ■ 

Energy delivered in K.W. to step-up transformers = energy 

K.W. I 2 X R X 2D 

delivered by generators = 1 (o) 

J 5 M X M t M, X 1,000 w 

Apparent energy in K.W. delivered by step-up transformers 

K.W. I X line drop 

= + (10) 

M X F 1,000 

Apparent energy delivered by generators to step-up trans- 

K.W. I X line drop 

formers = 1 (11) 

M X M t X F 1,000 XM 1 

E. = E + line drop (approximately) (12) 

For three-phase lines the formulas become: 

K.W. 
Energy to step-down transformers =- (1) 

K.W. 

Apparent energy to step-down transformers = (2) 

K.W. X 1,000 E 

1 = =in which E =- = effective voltage. 

3 X M X F X E e 1.732 

„ K.W.- X 1,000 X P 

R = (14) 

3 X D X I 2 

This result is in ohms per 1,000 feet per wire. 

Resistance drop = I X R X D (15) 

t> ♦ a QXIXDXN 

Reactance drop = (16) 

120 

Line drop = V(resist. drop) 2 -f (reac. drop) 2 i 1 !) 

Energy delivered by step-up transformers 

K.W. | 3(FXRXD) 

M 1,000 

8 



114 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

Energy delivered to step-up transformers 

K.W. 3 (I 2 X R X D) 

~ M X M x M x X 1,000 ^ 

Apparent energy delivered by step-up transformers 

K.W. 3 (I X line drop) 
= H (20) 

M X F 1,000 

Apparent energy delivered to step-up transformers 
K.W. 3 (I X line drop) 

" M XMxX F 1,000 X M x ^ 2I ' 

E = E + line drop (approximately) (12) 

All the foregoing are simply close practical approximations 
which are as near to the exact figures as standard sizes of wire and 
electrical apparatus make it necessary to come. The effect of 
capacity has been neglected as it is negligible except in very long 
lines — say 50 miles and above — unless the separate wires of the 
circuit are placed close together, and good practice prevents this 
closeness of conductors. The effect of the capacity current is to 
reduce slightly the apparent energy and the line current. It has 
no effect on the actual energy delivered. 

If systems are installed on the basis of the foregoing formulas 
and the lines are long, the only noticeable result will be a slightly 
less line drop and less heating of generators and transformers 
than the computations show. 

Aluminum Conductors. Aluminum is now used to a limited 
extent for transmission lines. Its weight is 0.3 that of copper for 
a given size and length of wire. Its conductivity is 0.63 that of 
copper. Therefore, for a given resistance per mile, the area of an 

aluminum wire should be =1.587 times the area of a copper 

0.63 

wire. As the area is proportional to the square of the diameter, the 

diameter of an aluminum wire must be 26 per cent, greater than the 

diameter of a copper wire for equivalent conductivity. The weight 

of aluminum compared to that of copper for a given conductivity 



TRANSMISSION CONDUCTORS 115 



0.3 



is equal to — — =0.476; that is, 47 J pounds of aluminum are equal 
0.63 

in conductivity to 100 pounds of copper. Therefore, the price 
which may be paid for aluminum to produce a given conductivity 

is = 2.1 times the price of copper. It should, however, be 

0.476 

bought at a lower price than 2.1 X cost of copper, as it is more 
difficult to join together and more trouble to put in place, owing 
to its comparative brittleness and softness. At 1.75 times the 
price of copper it will pay to substitute aluminum. 

The formulas and methods of computation before given for 
transmission lines apply equally to aluminum and copper conduc- 
tors. The size of the copper wire is taken from the table to corre- 
spond to the computed resistance. By adding 26 per cent, to its 
diameter, or 58 per cent, to the circular mils as given for the copper 
conductor, the size of the equivalent aluminum wire is found. 
Thus if the computed resistance is .0976 per 1,000 feet, this corre- 
sponds (nearly) to a No. o copper wire. The diameter of a No. o 
wire is 0.340 inch. Adding 26 per cent, this becomes 0.4384, 
which corresponds (nearly) to a 000 wire. Likewise, the circular 
mils of a No. o wire are 115,600. Adding 58 per cent, to this, the 
cir. mils are 182,600 which nearly corresponds to No. 000 wire. 
The computed size for aluminum is to be used for taking the reac- 
tance volts drop factor from the table. 

Solid aluminum wires are never used. Conductors of this 
material must always be stranded owing to its unreliability as to 
tensile strength in occasional spots. Also its brittleness makes 
the stranded conductors desirable. 

Arrangement of Wires. In the case of several single-phase cir- 
cuits, all fed from the same source and working in parallel, the 
wires may be arranged on the cross-arms in any convenient man- 
ner. If, however, two separate circuits fed from different dyna- 
mos run on the same pole line, the wires of each circuit should 
be placed as close together as conditions will allow, and the two 



Il6 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

circuits separated as much as possible. This is to avoid the effect 
of mutual inductance between the two circuits which will cause pul- 
sation in voltage that will seriously interfere with any lighting service. 

A better way is by transposing the wires, as shown in Fig. 52, 
which is a plan view. As indicated, the wires of one circuit run 
parallel, all the way from the station to the point of distribution, 
while the other circuit has the position of its wires transposed at 
the middle point of the line. 

In three-phase systems, the wires are usually placed in such posi- 
tions that lines joining their centres form an equilateral triangle, 
as shown in Fig. 53. Where a single circuit is placed on one pole, 



Fig. 52. 

no transposition is necessary. If two circuits be put on one pole, 
the wires of one circuit should run parallel, the wires of the other 
circuit being transposed twice in the entire length of circuit, the 
points of transposition being at one-third and at two-thirds the total 
distance from station to distribution point. 

In Fig. 54 the upper two circuits illustrate this arrangement. 
Fig. 55 shows the usual way of placing two circuits on a single pole. 
If a third circuit be placed on the same pole line with the first two, 
it must be transposed three times in the same distance that the sec- 
ond circuit is transposed once; or the distance apart of the trans- 
position points is one-ninth the total length of the line. The lowest 
circuit shown in Fig. 54 gives this transposition as related to the 
other two circuits. 



TRANSMISSION CONDUCTORS 



II 7 



All the foregoing is based on the arrangement of the wires of 
each circuit, so that any wire is the same distance from either of 
the other two, i.e., at the apexes of an equilateral triangle. If, 
however, the three wires of a circuit are all placed on the same 
cross-arm, so that they lie in the same plane, the wires of each cir- 




Fig. 53. 

cuit must be transposed. The transposition for one circuit on a 
pole is that of the middle circuit shown in Fig. 54; that is, two trans- 
positions in the length of the transmission, one at one-third, the 
other at two-thirds the distance from the power station. A second 



Il8 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

circuit on the same pole would be transposed like the lowermost cir- 
cuit shown in Fig. 54; i.e., a transposition at each one-ninth of the 
transmission length. 

A certain tension should be put on the wires in stringing them 



2 



3 1 2 

Fig. 54. 



on the poles, and it should be just great enough to give a definite 
amount of sag, or dip below the horizontal. The sag is dependent on 




Fig. 55. 

the length between spans and the temperature at the time of setting. 
A good rule is to allow a sag equal to 0.0155 X length between 



TRANSMISSION CONDUCTORS II9 

spans for a temperature of 6o° F. Increase or diminish the 
amount of sag thus found 7 J per cent, for each io° F. above 
or below 6o°. Thus, if spans are 200 feet, the sag would be 
200 X 0.0155=3.10 feet for 6o° F. If the temperature at the 
time of erecting were 90 F., the sag would be increased by a 
percentage = (90 — 60) X 7^ = 22 J per cent. 

22 J per cent, of 3.10 = 0.6975. Sag actual = 3.io + 0.6975 = 
3.795, say 3.8 feet = 3 feet 9 \ inches. 

The spacing apart of wires varies from 36 inches in short spans 
— say up to 150 feet — to 78 inches in long spans and with high 
voltages. Increasing the distance of separation increases the in- 
ductive drop, thereby increasing the size of generators and the 
line losses, while if placed too near together, the chance of swaying 
bringing the wires in contact, or the possibility of sudden high po- 
tentials, due to surging, causing a break-down at the cross-arms, 
is increased. 

Roughly, in transmissions up to 10,000 volts the distance should 
be 30 to 40 inches, up to 30,000 volts the separation should be 48 
to 60 inches, and a,bove 30,000 volts the distance should be 
about 66 to 72 inches. These distances vary somewhat with the 
length of span. 



CHAPTER X. 
Pole Line and Accessories. 

Supporting Poles. 

There is considerable controversy as to the best method of sup- 
porting the transmission wires. In all electrical lines worked at 
high voltages, every point of support is a possible source of trouble 
from leakage or break-down of the insulators. On this account 
the supports should be placed far apart. 

On the other hand, the greater the distance between supports, 
the greater is the strain on the wires and insulators, the sag is in- 
creased, the wires must be placed farther apart to prevent touching 
when swayed by winds, and this increases the inductive drop. 
Therefore, the spacing of poles or towers to carry the wires must be 
a compromise between these two opposing sets of conditions. 

In cold climates, the poles must be nearer together than in 
milder latitudes because of the possibility of an ice-coating forming 
on the wires. This may become so thick as to form a continuous 
cylinder having a diameter as much as i \ inches greater than that 
of the wire itself. Such a mass of ice adds greatly to the weight 
carried on the poles, and may cause breaking of insulator pins or 
rupture of the wire itself. 

The standard practice in the Eastern States, for pole lines, is 
about 150-foot spacing, or 36 poles per mile. In California and 
other Western States having mild temperatures, spans up to 500 
feet are being used. These conductor lengths are too heavy to 
carry on poles, and steel towers are substituted, which are made 
of ordinary structural-steel shapes, and weigh about 1 ,400 pounds for 
a 45-foot height, with cross-arms made of wrought-iron pipe, and 
proper provision for receiving insulator pins. Their present cost is 

120 



POLE LINE AND ACCESSORIES 121 

about 3 J cents per pound, or a 45-foot tower placed in position costs 
about $50.00. There are 21 of these in two miles, making the cost 
$1,050.00, or $525.00 per mile. Wooden poles of the same height 
and proper diameter cost with cross-arms about $7.50 each, set. 
Thirty-six of these for one mile cost, therefore, $270.00, or about half 
the cost of the steel towers. The poles, however, require replacing 
within from 10 to 12 years, while the towers will last indefinitely. 
The towers must be painted once every 18 to 20 months, which is an 
item of maintenance expense. Also, they allow the wires to ground 
if an insulator should fail. In their favor are their durability and 
the distance apart of the insulators. Their chief drawback is the 
first cost; and in spite of theory and calculations, the main object 
in view when installing a transmission plant is to get it into effi- 
cient and reliable operating form as cheaply and expeditiously as 
possible. After dividends have been declared a few years, and the 
wooden poles need to be replaced, the steel towers, bought with 
earnings of the plant, may be erected. 

When long spans are adopted, hard-drawn copper wires should 
be used. 

Poles may be of nearly any kind of growth that is strong, rea- 
sonably straight, and resists rot. White cedar, yellow pine, locust, 
chestnut, cypress, and spruce have all been used. 

White cedar and chestnut poles have an average life of twelve 
years, pine eight, cypress fourteen, and red cedar eighteen years. 
Concrete poles reinforced by iron bars have been lately tried and 
found to be satisfactory in every respect except the initial cost, 
which is about three times that of wood poles. 

The height of poles depends on local conditions. In open 
country, on a private right of way, the lowest wires should be at 
least 28 feet above the ground. In passing over roadways or popu- 
lated districts the wires should be at least 45 feet above the ground, 
and 55 feet is a better height. 

The length of poles should be about 12 J per cent, greater than 
the height above ground, which excess is the length to be set in the 
ground. In soft marshy earths the depth in the ground should 



122 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

be greater. No pole should be set with less than four feet in the 
ground. 

Poles must be amply proportioned to carry the various loads 
imposed on them by the pull of the wire, due to its weight between 
spans, the weight of the largest possible ice-coating, the wind press- 
ure, and the strain set up when the direction of the wires is changed 
producing an unbalanced pull on the poles. In the last case 
the pole is braced by heavy guy wires running from a point near 
the top of the pole to a short heavy stub and fixed firmly in the 
ground at some distance from the pole. 

The following proportions are usual in practice: 

Poles 35 feet high should have a circumference of 18 inches at 
the top, 45-foot poles 22 inches, 55-foot poles 24 inches. 

In setting poles, the butts should be given a good coating of hot 
pitch or asphaltum, if they have been previously seasoned. Green 
poles should not be so coated, however, as it hastens their decay 
by imprisoning the moisture in an impervious covering. When 
covered with pitch, the coating should extend up at least a foot 
above the ground line. 

In many cases, two separate pole lines have been erected each 
carrying its own circuits, so that, in event of accident to either, it 
can be switched out of service and repairs made while the other line 
carries the load, with a greater drop and line loss. This is, of 
course, an excellent arrangement, but its cost is high and a dupli- 
cate pole line should more properly be paid for by earnings pro- 
duced by a single line. 

Where the line passes through wooded country, the trees on 
either side must be cut down, so that no tree is left near enough 
to the line to reach it if uprooted or broken off. Also duplicate pole 
lines should be set apart far enough to prevent a broken pole on 
either line from falling against the other line. 

Cross-arms. These may be of any of the woods which are 
strong and durable. Yellow pine is used more than any other 
material. 

The usual cross-arm is a rectangular bar varying from 2 J X 



POLE LINE AND ACCESSORIES 1 23 

3 J to 4 J X 6 inches in cross-section. The upper surfaces are 
beveled to allow water to run off freely. 

They are set in shallow recesses or gains cut in the pole, and 
bolted on with two bolts each of from J to J inch in diameter, 
which pass through pole and cross-arm and are fastened with nuts. 
Large washers are put on the bolt at each end to make a good 
bearing surface against the wood. The arms are further fastened 
by bracing, the usual form of brace being a pair of flat galvanized 
iron strips about J X ij inches in cross-section, with a hole in 
each end. One \ X 5 inch lag screw passing through the holes in 
the two braces, kid one on top of the other, holds these ends to the 
pole. The other ends are spread apart and fasten to the cross- 
arm with a J X 3 inch lag screw through each. 

A pole head for a three-phase circuit is shown in Fig. 52 and 
gives these details. 

Usually, cross-arms are boiled in linseed oil for several hours 
to preserve them, and then painted. In any case they should be 
painted with a good weather-proof paint. One of the best in- 
vestments is to use large, strong cross-arms. The large sizes cost 
but little more than the smaller ones, and one of the weak points is 
at the cross-arms. Never use a size smaller than 3 J X ^\ inches. 

Insulators. There are two prime requisites for any insulator; 
it must have a high insulating quality and it must possess mechan- 
ical strength. All the strains in the line, the weight of the wires, or 
the stresses set up by wind and swaying must be taken by the in- 
sulators, and the element of mechanical strength is the really im- 
portant factor. 

For this reason, porcelain insulators are preferable to glass ones, 
provided the porcelain is high grade and well burned until it is 
vitreous throughout. 

Glass insulators, however, have been used in high-tension trans- 
mission work up to 40,000 volts with marked success, and their 
lower cost makes them attractive. 

The controversy of glass versus porcelain which endured so long 
has practically been settled in favor of porcelain, due no doubt to 



124 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

improved methods of manufacture and the resulting betterment 
of the quality of the latter. Some engineers still use glass, however, 
and find them satisfactory. 

Types of insulators are many and various, and their descrip- 
tion here would be out of place. 

Never put an insulator in place on a high-tension line without 
first testing it for dielectric strength. The test is standard and 
simple. 

Invert a number of insulators in a pan of salt water, of sufficient 
depth to cover about seven-eighths of the insulator. Fill the up- 
turned pin opening in the centre of the insulator about half full 
of salt water. Be sure that the insulator is fairly dry from the sur- 
face of the water in the pan to the water in the inner hollow of the 
insulator, by wiping off spilled water. Put a metallic pin or a car- 
bon rod — an ordinary arc-lamp carbon does very well — into each 
of the pin openings so that it reaches to the bottom. Connect the 
pan to one terminal of the secondary of a transformer, and the rods 
or pins to the other terminal. The transformer should give a po- 
tential of three to four times that of the line the insulators will be 
used on. Switch on the current to the primary of the transformer. 
Defective insulators will be ruptured and their pressure indicated 
by vicious arcing. A fuse must be placed in the circuit to the pri- 
mary of the transformer to protect it when the insulators give way. 

To test the quality of the porcelain in insulators, break one in 
pieces. Put red ink on the fractures and allow it to dry, then wash 
the fracture thoroughly. If the ink washes off clean, the porcelain 
may be considered as good quality and without absorptive power. 
If the ink does not wash off, the porcelain is not suitable for 
insulating purposes. 

The cost of high-tension porcelain insulators runs from 50 
cents to $2.00 each. Glass insulators cost from 10 cents to 40 
cents each. The use of glass should be limited to voltages of 
30,000 volts or under. 

Insulator Pins. These are made of both wood and iron. 
Various kinds of woods are used, but locust is the best. 



POLE LINE AND ACCESSORIES 1 25 

The pins must be strong enough to take the various line strains 
before set forth. Experience shows that the standard pin, having 
aif inch diameter at the shank (i.e., the lower end, which fastens 
into the cross-arm), is not sufficiently strong to carry the large wires 
over long spans that are now encountered in transmission work. 
No wooden pin should be less in diameter than 2 inches at the shank; 
and if the length of the pin above the cross- arm — that is, exclusive 
of the shank— should exceed 11 inches, the diameter should be 
made greater. In fact, 2| inches diameter for pins 16 inches 
long is not excessive. 

It is, of course, understood that the cross-arms are of proper 
thickness, which is 2 inches greater than the diameter of the pin, 
giving not less than 1 inch of stock on either side of the pinhole. 
The length of the shank should be the same as the depth of the 
cross-arm, so that the shank passes through the cross-arm from 
top to bottom. The pins are held in their sockets by passing a 
f-inch coach bolt through the cross-arm and each pin shank. 

Wood pins should always be boiled in linseed oil or stearic acid 
for several hours before putting in position. 

There are several varieties of iron pins. In one form the pin 
is made of f-inch rods threaded to screw into a cast-iron upper 
piece, which latter has approximately the dimensions of a wooden 
pin. The insulator screws onto this casting. 

Another form comprises a hollow porcelain shape, having 
proper dimensions to fit into the insulator, an iron pin passing 
through the porcelain piece and through the cross-arm. 

Wooden pins are subject to deterioration from charring, burn- 
ing, and softening. The first two come from leakage currents 
which manage to find a path due to the accumulation of dust, dirt 
and sometimes moisture. Softening is produced by the "brush 
discharge" from the line, which produces minute quantities of 
nitric acid. This eats into the wood and destroys it. Iron pins 
are not subject to any of these troubles, and their superior strength 
would seem to make them the best form of pin. They, however, 
lack the insulating quality of the wooden pin, they are more con- 



126 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



ducive to leakage currents and insulator break-downs; are more 
expensive to install, and tend to loosen in their sockets if the cross- 
arms are of wood. Therefore, the wooden pins are used on the 

majority of transmission lines in this 
■ a country. The use of iron pins, how- 

|1 ever, is increasing, due to the better 

grade of insulators now obtainable. 

Insulators set on iron pins should 
always be held in place with cement. 
Ordinary Portland cement, made to a 
thick paste with water is very good, or 
melted sulphur may be used. 

A recent method of supporting trans- 
mission conductors eliminates the insu- 
lator pins, and suspends the wires below 
the cross-arms by means of insulating 
suspension links. These links are of 
two types, comprising those which are 
meant to hang vertically and those which 
catch the end of a wire and hold it to the 
pole and have a horizontal position when 
installed. 

Fig. 56 shows a series of three of 
these vertical suspension links, while 
Fig. 57 shows three horizontally stretched 
links, Fig. 58 being a section through 
1 one of the latter which shows the 
method of constructing these insulators. 
They are made of porcelain discs 
having spherical-shaped portions in their centres. Two semicir- 
cular tunnels, at right angles to each other and interlinked, 
are formed in the spherical portion, one tunnel passing in one 
from one side of the disc and back out the same side, while the 
other tunnel passes in from the opposite side and back out 
on the same side it enters. The construction is clear from 




Fig. 56. 



POLE LINE AND ACCESSORIES 



127 



the figures, and it is obvious that the strain on the porcelain is 
compressive. 

Figs. 59 and 60 show the methods of using these link insulators. 
Fig. 59 shows the suspension of a wire hanging from a cross-arm 




Fig. 57. 

and below it. Fig. 60 shows the horizontal or tension link insula- 
tors attached to a supporting tower, and to which the ends of the 
transmission wire are fastened. The wires are in the latter case 
practically "dead-ended," but the line is made continuous by a 

loose connecting wire which joins 
the two conductors as indica- 
ted in the figure. The preferred 
practice is to use the tension in- 
sulators about every mile, and 
suspension insulators at the inter- 
mediate supporting points. This 
produces independent sections of 
wire, each one mile in length, 
supported at proper intervals. 

With these insulators any 
practical attainable voltage may 
be used, as each disc is capable 
of carrying 25,000 volts with a 
factor of safety against arcing around from one face to the other 
of about 2\. For higher voltages the insulators are simply placed in 




Fig. 58 



128 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

series, two being required for 50,000 volts or four for 100,000 volts. 
Owing to their great strength which enables each insulator to sup- 
port a load of three tons without rupture, the weight of wire 





Fig. 59. 



Fig. 60. 



between spans, and consequently the length of spans, may be 
very great. Ten poles or towers per mile is the spacing that has 
been adopted for one transmission line using these insulators, 

and spans up to 1,000 feet in 
length may be safely carried. 

The diameter of the discs 
is 10 inches for 25,000 volt un- 
its and 6 J inches for 12,000 
volt units. If the porcelain 
should crush or be otherwise 
shattered, the line does not 
fall, as the interlinked wire 
loops passing through the tun- 
nels in the porcelain simply 
come together and take the 
strain. Fig. 61 shows a broken 
insulator and the resulting 
linking together of the wire 
loops. Fig. 62 shows in outline the arrangement of two three- 
phase circuits on a tower, the voltage being 100,000. The wires 
are not arranged triangularly and therefore must be transposed, 




Fig. 61. 



POLE LINE AND ACCESSORIES 



I29 



as directed in the previous chapter, in order to balance static 
and inductive effects. 

Fig. 63 shows the general layout of a two-circuit, three-phase 
line for 80,000 volts, the wires being placed in a right triangular 
relation, so that the inductive effects are approximately balanced. 



HOR. SECTION A-B 
HOR. SECTION C-D 




END ELEVATION 



1 1 

side elevation hor. section g-h, 
Fig. 62. 



The advantages over the ordinary pin-and-insulator construc- 
tion claimed for this system of supporting wires are: 

(a) With the standard type of pin insulator now used, the 
difficulties of construction increase very rapidly at the higher 
voltages. The cost of insulator for a given margin of safety in- 
creases for voltages above 60,000 nearly as the cube of the increase 
in voltage. Either very large petticoat diameters must be used 
or very high insulators with many petticoats. In either case the 
9 



I30 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

manufacture of the porcelain parts is a difficult and expensive 
matter ; and with the long pin necessary, the mechanical stresses 
from the line on insulator, pin, and cross-arm are objectionable. 
With the series unit system here proposed, the cost of insulators 



HOR. SECTION A-B 
-10-9." 



f- 


/ 


/ 





. HOR. SECTION C-D 
Lightning Arrester Wire 



Transmission 
. Wire 

L 







END ELEVATION 



S//SS////////S//s^////s%/// 



SIDE ELEVATION 



Fig. 63. 



progresses only in direct proportion to the increase in voltage, the 
only change being in the number of units in series. There is 
practically no limit to the degree of insulation obtainable. 

(b) One of the most difficult elements of design in a trans- 
mission tower where long pins and petticoat insulators are used is 
to obtain a cross-arm which will resist the torsional stresses due 



POLE LINE AND ACCESSORIES 131 

to the leverage of the pin. With the pin entirely eliminated, the 
stresses are directly applied to the cross-arm; this cheapens the 
construction of the tower. 

(c) In the arrangements shown, where the insulating units are 
attached on either side of the cross-arm, taking the full tension 
in the line with jumper connections between spans, the insulation 
can be increased indefinitely by adding discs in series without in- 
creasing the space occupied on the tower. 

(d) Where each span is dead-ended, as in (c), all faces of the 
insulating units are exposed to the cleansing action of the rain, 
so that dirt cannot accumulate thereon. This arrangement also 
prevents the dripping water from forming electrical communication 
between units, as occurs from one petticoat to another in the pin 
type of insulator. 

(e) A standard insulating unit can be adopted for all volt- 
ages, the only variation being in the number linked in series. 

(f) If any insulating unit becomes damaged or completely 
shattered, the insulation of the remainder is not affected. The 
damaged unit can be replaced without the necessity of renewing the 
whole. / 

(g) If a tower is directly struck by lightning, the cross-arms 
will be likely to take the discharge, since they are above the lines, 
whereas in the pin type of insulator the line is usually the highest 
point. 

(h) In long-span installations, where the conductor at each 
end of the span is tied fast to an insulator mounted on a pin, 
experience has shown that crystallization is apt to take place in 
the conductor and the tie, due to its rigidity at that point and the 
vibrations in the span. This frequently results in breakage of the 
conductor. The flexible connection between conductor and cross- 
arm afforded by the series of insulators should reduce this tendency 
to crystallization, and should therefore permit spans of any length 
to be used without further precautions against this action. 

It might appear that with the conductor suspended under the 
cross-arm, serious swinging to and fro would take place. From 



I32 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

numerous observations it is believed that no such swinging will 
occur. Long aerial spans under wind pressure take a permanent 
and steady deflection throughout the span proportional to the 
average wind velocity along the span, and no indications have 
been observed of long spans responding to gusts. The towers 
are designed so that the conductor can safely be deflected 
by the wind about sixty degrees on either side of the neutral 
position. 

Exit from Power-house. Where the high-tension wires leave the 
power-house, they must pass through the wall or roof in such a 
manner as to avoid the possibility of touching any part of the 
structure, and the ingress of rain is prevented. 

Several excellent methods have been devised for the exit of the 





& B & B & B j^^g^ 



SECTION 



FRONT VIEW 



Fig. 64. 



line wire. One is shown in Fig. 64 which is suitable for voltages 
up to 30,000 volts. 

Tile pipes 12 inches in diameter, and spaced 14 to 16 inches 
between centres, are set in the walls sloping downward from in- 
side to outside, as shown. The slope may vary from twenty to 
thirty degrees to the horizontal. 

The wire passes from insulator A inside the station, through 
the tile pipe, to insulator B outside the station, the positions of the 



POLE LINE AND ACCESSORIES 



*33 



insulators being fixed to keep the wire in the centre of the pipe. 
The downward slope of the wire is to prevent water on the wires 
from draining into the power station. 

Another excellent arrangement is that shown in Fig. 65. 

The roof of the power-house is extended out about four feet 
beyond the wall, and a small box-like room is built below this ex- 




Fig. 65. 



tension, as indicated. Holes in the wall — one hole for each wire, 
the diameter being 12 to 14 inches — allow the wires to pass from 
the interior of the station into this compartment. The floor or 
bottom of the compartment has holes in it so that the wires may 
be turned downward and carried out through them. Two pairs 
of insulators or brackets serve to support and guide the direction 
of the wires. The compartment further serves as an enclosure 
for the lightning arresters, which are installed as shown. 



134 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

Other methods involving the use of openings covered with glass 
plates, each plate having a small hole in it for the wire to pass 
through, have been used. There is, however, always danger of 
dirt and dust collecting on the plates and providing leakage paths. 
The general opinion now is that a simple hole of twelve to six- 
teen inches diameter is the best construction. 



CHAPTER XI. 

Lightning Protection. 

Under the general classification "lightning arresters" come all 
that class of devices for protecting a line and the machinery at 
each end of it from sudden excessive potentials. These may arise 
from lightning striking the line, or any atmospheric, electrical dis- 
turbance that causes a high potential to build up between the line 
and the earth. Also, static charges, resonance effects, and surging 
produced by abnormal conditions in the line may produce a high 
potential the action of which is similar to that of atmospheric dis- 
turbances. These potential differences cause discharges tending 
to equalize themselves, and in every case the charges may be dis- 
sipated by a connection of the line to the earth. Unless some path 
is provided for them, they will go as near to earth as possible by 
the route of least resistance, i.e., the machinery, and jump through 
insulation and air to ground, and in their passage will melt wires 
and destroy the insulation. 

Also, lightning splinters poles and cross-arms and breaks in- 
sulators. 

To prevent the line potential from rising to an excessive value 
above that of the earth, barbed wire strung on insulators on the 
same pole line, above the transmission wires, has been used. The 
barbed wire is well connected to earth about every quarter of a mile. 
The barbs offer multitudinous points for the discharge of static 
electricity, and they are always at the potential of the earth because 
of the numerous ground connections. Therefore, the region sur- 
rounding the wires of the line are kept continually at the same 
potential as the earth. 

This arrangement, while helpful, does not alone meet the neces- 

135 



136 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

sities of the case, and in addition to it other forms of lightning 
arresters must be installed. 

The standard lighting arrester now in use is made up of a num- 
ber of small knurled metallic cylinders, set side by side in a por- 
celain frame and separated from each other by small air gaps. A 
cylinder at one end of the group is connected to the line ; the cylinder 
at the other end is connected to the ground. The air gaps prevent 
the normal line potential from sending current to the earth by this 
path, but excessive potentials will jump the gaps from cylinder to 
cylinder until the ground wire is reached. 

In order to make these arresters effective, there must be some 
device to oppose the rush of discharges to the station and compel 
them to take the path to the ground through the lightning arresters. 
Choke coils, or flat coils of copper wire or ribbon which have a 
copper area sufficient to carry the line current easily, present a 
barrier to the passage of lightning or other high-frequency dis- 
charges. The inductance of the coils creates but little opposing 
voltage to the line current, of 25 to 60 cycles per second frequency, 



Choking Coils 



Transmission Line 



M 



o'So^o 
0S0 So 
o spo £o 

l^O<!i 



To Transformers 



Fig. 66. 



but in the case of oscillatory discharges, where the frequency may 
run up into the millions, the opposition to the passage of such dis- 
charges is so great that the path through the arrester air gaps is 
the easier. 

Fig. 66 shows the connections for lightning arresters and choke 



LIGHTNING PROTECTION 



137 



coils, between the transformers or generator and the line. The 
arresters are each connected on one side to a line wire, and on the 
other side to the earth. 

Lightning arresters are almost valueless without choke coils. 

A form of combined lightning arrester and choke coil is de- 



to mACHs«e 




rouN€ 



SPARK SAf 




OROi/MB 



GROUND 



TO MACHJ?i£ 



END VIEW 



SIDE ELEVATION 



Fig. 67. 

picted in Fig. 67. This has been successfully used in Europe, and 
possesses certain advantages. 

It comprises several cast-iron shapes, shells, and diaphragms 
which when assembled together form an egg-shaped structure as 
shown. These several cast-iron parts are connected together by 
copper wires, the various sections being in series. From the last 
section on one side a connection is made to the choke coil, and from 
the other terminal of the choke coil the wire passes to the dynamo. 
The line wire is attached to the first of the cast-iron sections. 
Near the ends of the structure are placed horn-shaped pieces of 
metal, the distance of separation between the end and the horn- 
shaped piece being adjusted to form a discharge air gap, the latter 
pieces being connected to the ground as shown. The current from 
the dynamo passes through the choke coil, thence to the cast-iron 
piece connected to it, then, by means of the short connecting wire, 
to the next cast-iron piece, and so on until it reaches the line. The 
electrical resistance of the device is so small as to be negligible, and 



138 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

the inductance of the choke coil is low, so that but little opposition 
is offered to passage of the normal station count. When, however, 
a sudden charge, seeking earth, comes in over the line, it spreads over 
the large surface presented by the shell and tends to charge it 
electrostatically, which condition causes a concentration of potential 
at the pointed ends of the shell also. The rapid passage from cast 
iron to copper, again to cast iron, and to copper, and so on through 
the several sections of the shell, combined with the action of the 
choke coil, sets up a strong retarding action to the passage of high- 
frequency currents, which compels the charge to pass across the 
air gaps to the horn- shaped pieces and thence to earth. 

Another good form of lightning arrester is known as the horn 



Copper Wire 




Ground 



Fig. 68. 



type. This is made of ordinary copper wire size No. 000, bent 
in the form shown in Fig. 68. Two of these bent pieces supported 
on insulators form an arrester; one horn is connected to a line wire, 
while the other is connected to the ground through a fuse. 

The dimensions given in the figure are those for a 5o;ooo-volt 



LIGHTNING PROTECTION 



J 39 



system. For smaller potentials the air gap between the horns is 
correspondingly diminished. 

A simple and effective form of arrester used in Europe com- 
prises a plate of copper attached to each of the line wires against 
which a small stream of water is thrown from a nozzle. The re- 



Horn.LightDing 
, Arrestersi 




To Transformer, 
Choking- Coils 



Tig. 69. 

sistance of the water is too high to allow any appreciable leakage 
of current, but forms a good path for lightning or static discharges. 

To thoroughly protect a line there should be installed two 
choke coils in series with each wire, and two different forms of 
lightning arresters attached to the line next to the outer choke coil, 
and two more arresters of different types installed between the choke 
coils ; and this arrangement should be duplicated at both ends of the 
line. Fig. 69 indicates this method of protection, using standard 
cylinder arresters and horn arresters, a single wire only of the cir- 
cuit being shown. 

In long lines standard or horn arresters should be placed every 
two or three miles along the line, the distance apart depending on 
the frequency and violence of thunder-storms and other atmos- 
pheric electrical disturbances. 

In regions where such phenomena are frequent, it is advisable 
to use the overhead barbed wire, before described, in addition to 
the lightning arresters along the line. 

Unless the ground connections are all well made to some point 
which is continuously damp, they will not form the required low- 



140 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

resistance path to earth. If it is necessary to locate them where 
the ground is always dry, a small water pipe should lead to the 
earth at the ground connection and enough water allowed to con- 
stantly drip to keep the place damp. The ground connection to 
the arrester may be made by connecting to water pipes where 
they are two inches in diameter or greater ; in other cases copper 
plates not less than two feet square and one-sixteenth inch in thick- 
ness should be sunk in the ground to a depth of five feet or more, 
depending on the depth at which permanent dampness is reached. 
Coke, broken into fine particles, is packed on either side of 
the plate, the thickness of the coke being at least six inches; the 
ground wire is securely soldered or brazed to the plate and carried 
straight upward to the ground terminal of the arrester. The ground 
wire should be No. oo solid copper. If possible there should be 
no bends in it whatever; and if there are more than two ninety- 
degree bends in it, its efficiency will be impaired. 



CHAPTER XII. 
Switching and Controlling Apparatus. 

All switches for potentials above 2,000 volts should be of the 
kind that have their blades and clips submerged in oil and known 
as oil switches. The switches themselves are placed back of the 
switchboard, and manipulated from the front by means of handles 
that pass through the board to the front, and which connect by 
rods or links with the switching mechanism. In some cases the 
switches are placed on the wall in the rear of the switchboard, the 
handles being on the front, and connecting by links or rods to the 
switches. A standard switch of this type is shown in Fig. 70. 

This arrangement is suitable for pressures up to 10,000 volts. 
Above this, the switches should be placed in brick or concrete 
chambers beneath the switchboard and worked by handles on the 
board mechanically connected to the switch gear. In the case of 
large switches for high potentials, the switch, instead of being moved 
directly by hand, is operated by a motor or a large magnet which 
is controlled by a small, low-potential hand switch. Current from 
the exciter dynamo is generally used to work the motor or magnet 
moving the switch. 

These switches may be made to open automatically with ex- 
cessive current flow, by means of a controlling magnet to actuate 
the switch that sets in motion the operating magnet or motor, the 
magnet being set to move when the line current exceeds a certain 
predetermined value. When so arranged, they serve the double 
purpose of automatic circuit breakers and hand switches. 

When the potential exceeds 10,000 volts and the amount of 
energy transmitted over each switch is 350 K.W. or. more, it is 
advisable to place each pair of contacts in a separate fireproof 

141 



142 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



chamber; that is to say, a three-phase switch becomes, in effect, 
three single-phase switches, all actuated simultaneously by a single 
mechanism common to the three. The high-tension bus-bars are 
also enclosed in a long horizontal fireproof compartment which 
runs along just above the switch compartments. The sides of this 
bus-bar chamber may be made of brick, tile, or concrete. Fig. 71 
shows a high-tension switch for 60,000 volts with its three contacting 




Front. 







Rear. 
Fig. 70. (Oil Chamber Lowered.) 



parts in three separate brick chambers. This switch is operated 
electrically by heavy magnets which may be partly seen, their 
plungers connecting to the operating- chain links attached to the 
main lever arm. 

Ordinary knife switches are satisfactory up to 600 volts; and 
where the energy transmitted over each switch does not exceed 500 
K.W., these may be used as main dynamo switches with low-ten- 
sion generators, the voltage being raised by step-up transformers. 



SWITCHING AND CONTROLLING APPARATUS 



J 43 



These also are used for the exciter dynamos and the generator 
fields. 

The exciter current is usually of low voltage, either 125 or 250 
volts, and the exciter switchboard is built on the same lines and 




Fig. 71. 



principles, as those which guide the design of any direct-current 
switchboard, the instruments being mounted on marble panels 
from 1 J to 2 inches thick, which are in turn supported on vertical 
sections of angle iron, to which the slabs are bolted. Felt or rubber 
washers about one-eighth inch thick should be interposed between the 



144 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

iron and the marble. Adjacent panels are joined together by bolt- 
ing the adjoining webs of two separate supporting angle bars to- 
gether by | -inch bolts, spaced 18 to 22 inches apart along the 
length of the angle sections. Fig. 72 is a plan view showing a por- 
tion of two adjoining marble slabs each bolted to its supporting 
channel bars, the latter being bolted together. An angle section 



)4 Bolts,brass cone-head nuts 




2 X 2\ inches is a good size to use, the narrow web being bolted 
to the marble. 

It is customary to install a separate panel for each dynamo. 
The exciter panels are usually placed at one end of the board, and 
the generator panels at the other end. A totalizing panel is gener- 
ally put in the middle of the exciter panels on which are mounted 
instruments to show the total output of all the exciters working to- 
gether, while a totalizing panel for the purpose of registering the 
total output of the generators is put in the middle of the generator 
panels. 

There have been a number of methods suggested for switch- 
board and switching connections, some of which are highly com- 
plicated; and the multiplicity of connections and the numerous 
switches are more liable to prove sources of trouble than to be 
of much assistance. Furthermore, high-tension switches are ex- 
pensive and, unless carefully worked out, the switchboard may be 
a source of great and unnecessary expense. Fig. 73 shows an 
arrangement which the author considers amply complete and 
flexible. G v G 2 , and G 3 are three-phase generators excited by fields 
F v F 2 , F 3 . The generators connect through the generator switches 



SWITCHING AND CONTROLLING APPARATUS 



145 




Fig. 73. 



10 



146 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

to a set of three-phase, low-tension bus-bars. T v T 2 , T BJ T 4 are 
step -up transformers connected in mesh as shown, and any trans- 
former may be joined to the low-tension bus-bars by means of the 
low-tension transformer switches which connect to the transform- 
er primaries. These generator and transformer switches may 
be ordinary knife switches if the voltage of the generators does 
not exceed 600 volts and the K.W. capacity is not above 500. 
It is well, however, to use automatic circuit breakers, which may 
be tripped by hand, for the generator switches, and these will dis- 
connect in case of overload or can be operated manually when 
desired. 

A set of high-tension bus-bars has a series of high-tension 
switches connecting them to the step-up transformer secondaries, 
and the outgoing transmission lines are joined to the high-tension 
bus-bars by high-tension switches similar to those connecting the 
transformer secondaries to the high-tension bus-bars. The trans- 
mission line switches should be provided with automatic tripping 
coils which will cause them to open if the current should exceed a 
predetermined amount. 

E x and E 2 are exciter dynamos which connect by means of 
ordinary knife switches to the exciter bus-bars. The generator 
fields also connect to the exciter bus-bars each through its own 
field switch as shown, the current passing through the generator 
field rheostats H 1} H 2 and H 3 . By means of rheostats R ± and R 2 
the voltage of the exciters may be adjusted. These machines may 
be run in parallel or either one, singly, can be used to supply current 
to the exciter bus-bars. The field of any generator may be switched 
onto or off from the bus-bars, and each generator field may be in- 
dividually adjusted by means of the rheostat in its circuit. Any 
of the main generators may be switched on or off the low-tension 
bus-bars, any transformer may be cut out of service, and either of 
the transmission lines or both may be disconnected. 

This diagram does not indicate any instrument connections 
except that of the synchroscope. As shown, this is connected to 
the generator bus-bars by means of a small switch on one side. 



SWITCHING AND CONTROLLING APPARATUS 



147 



Its other side connects to several small switches — three in this 
case. By plugging in the switch to the bus-bars and any one 
of the switches connected to the generator terminals, the relative 
frequencies of the bus-bar and the generator to which the instru- 
ment is connected are indicated. This device is for the purpose 
of showing whether the frequency of a generator, which is not 
connected to the bus-bars, is greater or less than that of the bus- 
bars, so that the speed of the disconnected generator may be raised 
or lowered until the frequencies are the same; and when this con- 
dition is reached, the pointer comes to rest in its middle position 
and thereby indicates that the synchronized. generator is ready to 
be connected to the bus-bars, it being assumed that the voltage has 
been previously adjusted to its proper value. 

Voltmeters should be installed so that the following indications 
may be taken: 

1. Voltage of each generator. 

2. Voltage of low- tension bus-bars. 

3. Voltage of high-tension bus-bars. 

Up to 600 volts voltmeters are connected directly to the circuit 
to be measured. Above that, however, a transformer is connected 



\; 



MAMA 

-S4- 



\J~ 



AAAAAA 



AAAAAAA, 




Fig. 74. 



to the circuit, and the voltmeter is connected to the secondary side 
of the transformer. Fig. 74 shows a three-phase line with the 
primaries of three small transformers connected across the three 



148 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

phases. The secondaries leave the three small switches which 
latter connect to a pair of wires leading to the voltmeter. By 
throwing in any switch a single voltmeter is made to indicate the 
voltage of each of the three phases. Where three-phase systems 
are balanced — that is, equal current passing over each of the three 
wires — it is necessary only to take the voltage of one of the phases, 
as the voltages of all the phases will all be equal. This is the 
condition existing in nearly all transmission systems; and in 
them only one transformer with its secondary connected to the 
voltmeter is required. 

Ammeters on high-tension circuits are also connected to trans- 




Fig. 75. 

formers in which the primary consists of one or two turns in series 
with the main current. The secondary consists of a number of 
turns, its terminals being connected to the ammeter. Obviously, 
the volts generated in the secondary will be proportional to the 
current in the main line passing through the primary. The in- 
strument itself is in reality a voltmeter; but the movements of its 
needle being proportional to the current passing in the main line, 
the markings of its dial are in amperes. Fig. 75 shows the con- 
nections. 

Wattmeters record the quantity of electrical energy generated; 



SWITCHING AND CONTROLLING APPARATUS 1 49 

and the usual type of integrating instrument makes a continuous 
record of total energy delivered over a certain period of time. 
These have two windings, one a shunt, the other a series winding; 
and therefore, potential and series transformers both are required 
for them. 

Circuit breakers which work on high-tension lines must take 
current for the tripping coils from series transformers. It is cus- 
tomary, where ammeters, voltmeters, and wattmeters are to reg- 
ister on the same circuit, to put in one potential and one series 
transformer, each large enough to provide current for its instru- 
ment and the wattmeter also; and if a circuit breaker operate on 
the line, the series transformer is large enough to supply current to 
its tripping coil, in addition. 

Synchroscopes on high-tension circuits are connected to the 
secondaries of potential transformers instead of directly to the 
line as shown in Fig. 73. 

Other alternating- current instruments are, power factor meters 
and frequency meters. The former are not necessary except under 
certain special conditions, the second only a convenience and in no 
wise essential. 

Ground detectors are necessary in every plant. These indi- 
cate the existence of a contact between the earth and any one of 
the lines. The type of detector now used is electrostatic, in which 
no current passes through it. The connection is made either direct 
to the instrument or to the terminals of a condenser, the connec- 
tions in the former case being as indicated in Fig. 76. When 
connected directly to earth a fuse or graphite resistance must al- 
ways be placed in the ground connection so that in case of the 
vanes becoming bent so that they approach each other and an arc 
should leap across, the current flow would melt the fuse and pro- 
tect the device. 

A better way of installing these instruments is to use small con- 
densers which are supplied for the purpose. No matter whether 
the vanes are in contact or not, the current flow is so limited that 
neither the condensers nor the instrument can be injured. 



150 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

The relative value of circuit breakers and fuses is a subject 
still under discussion, and each case must be separately considered. 
Fuses, when properly made, can be used successfully under po- 
tentials up to 6,000 volts where the power does not exceed 100 K.W. 
Such fuses are from 12 to 18 inches in length and are surrounded 
by porcelain tubes, with sand packed in the tube around the fuse. 




With lower potentials, as much as 200 K.W. may be interrupted 
by fuses. In plants having units larger than this, automatic cir- 
cuit breakers should be used and made to serve at the same time 
as switches. 

In a properly designed switchboard there will be no parts on 
it carrying high potentials. The high-pressure switches and bus- 
bars will be in their fireproof compartment, with operating handles 
only on the face of the board — usually coming through the marble 
from the rear — or simply small, low-potential knife switches to 
actuate the operating magnets or motors which move the high-poten- 
tial switches. All instrument transformers are mounted either on 
the wall in the rear of the switchboard or on the horizontal iron 
braces running from the switchboard, to the wall, only the low- 



SWITCHING AND CONTROLLING APPARATUS 151 

tension wires from their secondaries going to the instruments on 
the board. 

The direct- current panels for the exciter have no special in- 
struments on them other than standard voltmeters, amperemeters, 
and knife switches, with the single exception of the field switches 
to the main generator fields. These are ordinary knife switches 
each having a pair of auxiliary contact clips which the switch 
blades do not touch when the switch is closed. In opening it, 
however, the blades touch these clips just before leaving the clips 
connected to the exciter bus-bars. The auxiliary clips are joined 
together by a resistance. At the instant when the switch blades 
are on the point of leaving the bus-bar clips and are making con- 
tact with the auxiliary clips, the resistance is connected in par- 
allel with the generator field. A further movement of the switch 
handle disconnects the blades from the bus-bar clips, but leaves 
them still in contact with the auxiliary clips, and the resistance be- 
tween these latter provides a path for the inductive discharge of the 
generator fields. Without such an arrangement, instantaneous 
potentials are set up on opening the field circuit which may be great 
enough to cause break-down of the insulation. 

In designing the board, allow not less than two inches between 
bare metallic parts of opposite potential for 125-volt boards and 
2 J inches for 2 50- volt boards. Keep at least 2 inches away from 
the angle-iron supports for the slabs. Current densities per square 
inch should be 1,000 amperes in bus-bars, 750 to 800 amperes in 
the switch blades and clips, 100 to 125 amperes between surfaces 
bolted together, and 50 to 55 amperes between switch blades and 
clips. 



APPENDIX 



COMPUTATION OF PRESSURES SET UP IN LONG PIPES WITH 
CHANGE IN GATE OPENING 



Abstract from a paper presented April 9, 1906, before the Ameri- 
can Institute of Electrical Engineers on 

A NEW METHOD OF TURBINE CONTROL. 

BY LAMAR LYNDON. 

In the case of a turbine fed by a long, closed pipe, it is evi- 
dent that any change in the gate opening must be accompanied 
by a change in the velocity of the column of water, and since 
this column has weight, velocity, and is practically incompressible, 
kinetic energy, proportional to its mass and the square of the 
velocity, is stored in the moving water, and any change in its ve- 
locity must be accompanied by a corresponding change in its 
energy, which can only take place by change in the internal 
pressure in the pipe. 

Starting with the formula, the basis of mechanics, 

F = M A, in which 

F = force or pressure in pounds; 

M = mass = weight in pounds nr 32.2; 

A = acceleration in feet per second; 
the change in pressures for changes in gate opening can be de- 
duced. 

Let S = area of pipe in square feet. 
L = length of pipe in feet. 
W = weight of a cubic foot of water = 62.5 lb. 

152 



APPENDIX I53 

Then S L W = total weight of water in the pipe at any time, 

S LW 

and its mass = (1) 

32.2 

If C t = velocity in feet per second with a given gate opening; 

C 2 = velocity with a reduced gate opening; 

T= time of change in seconds, 

then P, the pressure set up will be, 

p = SLW x C^ 

32.2 1 V ' 

which is the total pressure to retard the mass of water. 
If p= pressure in pounds per square inch, 

P SLW C.-C. ^LjC.-C,) 

P '" SXi44~SX I44 X 3 2. 2 r~ 74.3 T (3) 

this being the formula for excess pressure above that due to the 
head when the gate opening is reduced, or the reduction in press- 
ure to be subtracted from the head at the time when the gate 
opening is increased. It is to be noted that the pressures per square 
inch are independent of the diameters of the pipes. 

As an example, take a pipe 1,000 ft. long; head at the tur- 
bine 90 ft.; velocity of water in the pipe 6 ft. per second at full 
gate. Reduce this opening to 70 per cent, gate in three-fourths of 
a second. The reduced velocity of the water is 70 per cent, of 6 = 
4.2 ft. per second. 

1,000 (6 — 4.2.) 
* 74.3X0.75 d * 
The head on the turbine is 90 X 0.434 = 39 lbs. normal. Percent- 

32.3 
age change in the pressure is = 83 per cent. 

39 

If the gate were moved from 70 percent, to 100 per cent, opening 

as above, the net head acting for the short time of gate movement 

would be 39—32.3 = 6.7 lb., or about 17 per cent, of the normal 

head. 

When the gate is completely closed, the phenomena are very 

different, as are the laws which govern them. These will now 

be investigated. 



154 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

If the gate were closed instantaneously, the excess pressure 
set up would be infinite if it were not for the ductility of the con- 
ducting pipes and the elasticity of the water itself. Because of 
these effects, however, the pressures produced by instantaneous 
closing of the gate are not infinite, but, from a theoretical view- 
point, small, though exceedingly great when considered as hydrau- 
lic effects, to be taken care of in practice. 

For increase of pressure when the valve is closed instanta- 
neously the formula is 

■'■'-■ **gffi oEE't Z) (4)* 

v g{tE'+2RE)l 
in which 

p = increase in pressure per square inch; 
c = initial velocity in feet per second ; 

w = weight of a prism of water i ft. long and i sq. in. in cross- 
section =0.43416; 

E = modulus of compressibility of water = 294,000 lbs. per 
sq. in. = 294 X io 3 ; 

E' = modulus of elasticity of plate iron = 30,000,000 lbs. per 
sq. in. =3 X io 7 ; 

t = thickness of pipe plate in inches; 
g = acceleration due to gravity = 32.2; 
R = internal radius of pipe in inches. 

Take, for example, a pipe of 5 ft. diameter, the thickness of the 
pipe wall being 0.25 in., and the velocity of the water in the pipe 
being 6 ft. per second. Substituting the above values of a), t, and R, 

f=*U/ o-434X294Xio 3 X3Xio 7 Xo.25 \ 
^ 32.2(0.25 X 3X io 7 +2X3oX 294X io 3 )/ 



whence p = 6 X \/i,i82 = 206 lbs. per sq. in., — a pressure which 
approaches the rupturing point of the pipe. 

As may be seen, the pressure produced by instantaneous clos- 
ure is independent of the length of the pipe. An appreciable 

*Church's "Hydraulic Motors," p. 208. 



APPENDIX 155 

time, however, is required to close any valve, and with the in- 
troduction of the time element the length of the pipe also enters 
as a factor into the problem. The theory, in general, of the phe- 
nomena which take place on instantaneous gate closure is that 
the kinetic energy of the moving mass of water changes to poten- 
tial energy, distending the pipe and compressing the water. This 
compression of the water continues for only an instant, as imme- 
diately after compression it begins to extend itself; this act of ex- 
tension again sets up the pressure and causes compression. The 
cycle is repeated, and this continues until the friction of the water 
in the pipe and the molecules against each other decrease the 
amplitude to nearly zero. The whole occurrence is an oscillatory 
one and resembles somewhat the phenomenon of "surging" in 
electrical transmission lines carrying alternating currents. The 
velocity of the "wave propagation" is the same as the velocity of 
sound in water, and this velocity varies with varying conditions of 
thickness of pipe shell, modulus of material of shell, and its inter- 
nal radius. The formula for the velocity of wave propagation is, 



A /g EE't 

1 G>^tE'+2RE 



(5) 



* 



Formula (4) may also be written 



cvW 
P = — (6) 

in which v= velocity of wave propagation in feet per second; 
W = weight of a cubic foot of water. 

cW 

If p = 206 as given in the foregoing problem, 



t 
206 X i/u 

V 



206X144X32.2 - 

= - — - — - — = 2,^40 ft. per sec. 

6X62.5 '** F 



*Church's " Hydraulic Motors," p. 208. 

t Constant 144 is to reduce the cross-section of a cubic foot of water to 
square inches. 



156 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

Assume the pipe 1,000 ft. in length. Then the time required 
for the wave to travel from the gate back to the end of the pipe 

2X IjOOO 

and return to the gate is =0.788 second. This may be 

2,540 

termed the "time constant" of the pipe for the velocity of water 

flow of 6 ft. per sec, and designated by T . If the gate be closed 

within the time of one complete wave cycle, i.e., 0.788 second for 

this case, the pressure set up is the same as ij the gate had been closed 

instantaneously. 

If the pipe were 3,000 ft. long, the time constant would ob- 
viously be three times the above or 2.364, say 2 \ seconds, and, in 
order to avoid the heavy pressure computed, the gate must not 
close within this time of 2J seconds. 

If a longer time be taken to close the gates, the pressure set 
up will be directly proportional to pressure due to instantaneous 
closing in the inverse ratio of T to T , where T is the time in 

O C X 7 X 

which the gate is closed; that is, p : f/ f \\T : T x . Thus if 4.5 
seconds are taken to close the gate, for conditions as above and a 
length of pipe of 1,000 ft., the pressure produced will be 206 X 

= 36 lbs. For a 3,000-ft. length of pipe the pressure will 

4.5 

2.264 

be 206 X = 108 lbs. 

4-5° 
These formulas and facts have all been experimentally proved 

by Joukovsky in a series of experiments conducted at Moscow, 

Russia, in 1 897-1 898, in pipes up to 24 in. in diameter. They 

show conclusively the necessity for compensating for the change 

in energy in the water column at the time of governing, if the 

gates are to be moved quickly for rapidly fluctuating loads. 



PART III 

DESCRIPTIONS OF HYDRO-ELECTRIC GENERATING 
AND TRANSMISSION PLANTS. 

THE TOFWEHULT-WESTERWIK TRANSMISSION SYSTEM, 

SWEDEN. 

Abstract from " Electrical World " Sept. 28, 1907. 

An electrical equipment recently installed in Sweden for trans- 
mitting energy from Tofwehult to Westerwik possesses some 
interesting details, which are outlined below. The plant con- 
sists of a power-house at Tofwehult, a transmission line thence to 
the town of Westerwik, and transformer and converter stations 
in that town. 

The Power-house. 

The natural surroundings of the waterfall at Tofwehult rendered 
it especially favorable for development, because it is situated be- 
tween two lakes, and the connection between these, which forms 
the fall, consists of a deep cleft with almost vertical sides. In 
consequence the hydraulic work was very simple and cheap; 
the costs of the hydraulic work and the power-house building 
amounted to only $26,000, which, on the basis of the maximum 
output of 1,300 horse-power, including the reserve, is only $20 per 
horse-power. The power-house is built for three generating sets, 
two for 325 H. P. each, and one for 650 H. P. Only the 
two smaller sets are now installed. 

The turbines showed under test an efficiency at full load of 
81 per cent., and a speed variation of only 6 per cent, at a load 
variation from full load to no load. An interior view of the 
power-house is shown in Fig. 77. Each of the generators is built 

J 57 



I58 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

for 10,000 volts and 285 K.V.A. The major insulation of the 
armature coils consists of several layers of oiled cloth and a final 
coating of an insulating compound. At the insulation test of one 
of these coils, the break-down occurred at 45,000 volts. 

A separate extension of the power-house is provided for the 




Fig. 77. — Interior of Power-house. 

switch gear, as seen in the illustration Fig. 78. The lightning ar- 
resters are placed on the upper floor of this extension. The lower 
floor, which is separated from the generator hall by the switch- 
board, contains all other apparatus and instruments for low 
and high tension. The high-tension equipment is placed in a 
compartment separated by iron gratings and accessible from 
both sides. 

In order to prevent the accumulation of static electricity on 
the high-tension line a static protector is provided. This ap- 
paratus consists of six vertical glass pipes, two for each phase, 
(Fig. 78), through which water flows continuously. The upper 
connection between the two pipes of each phase consists of an iron 
faucet which is connected to the corresponding bus-bar. The iron 
pipes, through which the water is carried to and from the ap- 
paratus and which are connected to the lower ends of the glass 



TOFWEHULT WESTERWIK PLANT 



159 



pipes, are grounded. The water being very pure and therefore 
its specific resistance being high, the current leaking through 
the apparatus is small, amounting to only 0.036 amp. per lead; 




Fig. 78. — Lightning Arresters 



this value is probably rather too small to secure a good efficiency 
of the device. 

The High-tension Line. 

About half way between Tofwehult and Westerwik a deep 
bay of the Baltic cuts into the land. If the transmission line 
had been erected around this bay the length would have been 
increased by 3.75 miles above the straight distance of about 9 
miles between the power-house and the town. The increase 
could be avoided by crossing the bay by means of either a sub- 
marine cable or a long overhead span. In order to obtain suffi- 
cient security against break-downs of a cable in the middle of an 
overhead line of 10,000 volts it would have been necessary to in- 
stall special protection devices and to lay two cables. Even 
if these provisions had been made, the crossing by cable would not 



l6o DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

only entail a lower degree of working security, but would also 
cause higher running costs. Since, not far from the straight line 
between the power-house and the town, the bay forms a narrow 
strait with steep shores, it was decided to build at this point an 
overhead span of sufficient height to avoid all sails. The length 
of the span is 735 ft., and the height over the water is, at the lowest 
point, 131 ft. The conductors consist of steel wire ropes, each 60 
sq. mm. in cross-section; they are supported by iron masts, each 
having a height of 82 ft., two on each side, which carry insula- 
ting supports. 

A view of an insulating support is given in Fig. 79. It con- 
sists of an oak block, resting on six high-tension insulators. The 



Sheet lead 




Fig. 79. — Saddle Support For Long Wire Span. 

insulators are cemented to the oak block, their iron pins being 
fastened to the brackets of the mast. The oak block is protected 
against moisture by a coating of sheet zinc. In order to prevent 
the pull of the wire ropes from acting on the masts, a rolling de- 



TOFWEHULT WESTERWIK PLANT 



161 



vice is provided. The rolling device consists of a cast-iron plate 
resting on the oak block, four- cast-iron rolls, and a cast-iron piece 
which rests on these rolls and to which the wire ropes are fastened 
by screws. The terminals of the wire ropes are anchored to the 
rock. Thus they act as a guy to the casting to which the wire rope 
is fastened, and prevent it from rolling out of the cast-iron plate. 
Slipping to the side is prevented by flanges on the rolls. Four 
wire ropes are mounted in this way, one of which serves as reserve. 
As stated the cross-section of each rope is 60 sq. mm. Each 
wire rope has, therefore, the same conductivity as a copper 
wire about 7 sq. mm. in cross-section. . At 30 C. the strain in 
the span part of the rope is 1,300 lbs., and in the guy part 1,650 lbs. 
Thus the maximum stress equals 17,800 lbs. per sq. in., corre- 
sponding to a safety factor of 5. The sag of the rope at 30 C. 
equals 29.5 ft. In spite of this sag a contact between the ropes 




Fig. 80. — Method of Anchoring Wire Cable Span. 



is impossible, since they are mounted at different heights, and the 
horizontal distance of about 6.5 ft. is ample. Moreover, it has 
been proved that even in a strong wind the wires do not swing; 
all of the ropes are deviated to the same constant angle from 
the vertical plane whereby the distance between the ropes is 
not changed. 

As the wire ropes are anchored to the rock it is necessary to 



11 



1 62 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

put special-strain insulators into the guy part of the ropes. The 
strain insulator which is shown in Fig. 80 must withstand a me- 
chanical force of 1,650 pounds and at the same time secure a 
good insulation. The insulators are coupled in series by twos; 
therefore, at the regular working conditions each insulator is sub- 
jected to a voltage of 3,000. Still, in order to get a high degree 
of security, each insulator was designed for 20,000 volts. The 
insulator is covered on the top and sides by a cap of sheet zinc 
whereby it is perfectly protected against moisture. The dry insu- 
lator in actual tests withstood a tension of 25,000 volts. As to 
the mechanical strength a lining of sheet lead between the iron 
and the porcelain effects an equal distribution of the mechanical 
pressure upon the latter; and since porcelain possesses a great 
strength against pressure it was not difficult to make the span in- 
sulators sufficiently strong mechanically. 

A telephone circuit is erected on the high-tension line poles. 
For this line common telephone insulators are used; the tele- 
phone lines are transposed at every fifth pole. The high-tension 
line is transposed one turn at every 1,000 ft. In telephoning over 
this line a humming sound is heard. The noise is not so loud as 
to disturb the conversation. It is probably partially caused by the 
grounding of the neutral point at both the transformer station 
and (through the static protectors) in the power-house. 

Transformer and Converter Stations and Distributing 

Cable. 

In the main transformer station at Westerwik the current 
is transformed to 500 volts three-phase and 3,000 volts, three- 
phase. The former voltage is used for distribution within an 
industrial district in the neighborhood of the transformer sta- 
tion; the latter is used for transmission to the converter station 
which is built close to the old city plant. The converter station 
is arranged for four motor-generator sets; two of those are in- 
stalled at present. The direct E.M.F. is 2 X no volts, but every- 



TOFWEHULT WESTERWIK PLANT 163 

thing is so planned that later on an E.M.F. of 2 X 220 volts can 
be adopted without any difficulty. The station reserve equipment 
includes a storage battery, while the steam-driven direct-current 
generators of the old city plant also constitute a valuable reserve. 
Transformer station No. 2 supplies energy to some factories in its 
neighborhood by means of three-phase current at 500 volts. 

The distribution of the direct current used in private lighting, 
for small motors, and for the street lamps within the city is ac- 
complished by means of underground cables. The street lighting 
is furnished by 65 enclosed, 7 -ampere arc lamps. The lamps are 
connected two in series across the 2 20- volt supply mains. 

The costs given below refer to the two generator sets installed 
at the present time. The total cost of the fully installed power- 
house and equipment for 1,300 H.P. would be about $46,000. 
Referred to the entire equipment including the reserve, namely 
880 K.W., the cost was $52.70 per K.W. at the power-house and 
$65.40 at the end of the high-tension line; the corresponding 
costs per horse-power are $39 and $48, respectively. 

The following list costs of various items may prove of interest: 

COST OF EQUIPMENT. 

Dam and power-house $26,200.00 

Two 325-H.P. turbines and two 43-H.P. turbines. . . . 4,800.00 

Two 285-K.W. and two 30-K.W. generators 5,200.00 

Station wiring and instruments 1,900.00 

$38,100.00 
Nine miles (27 total) of circuit, 19.6 sq. mm., includ- 
ing poles and right of way $11,000.00 



,100.00 



164 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

HYDRAULIC DEVELOPMENT AT WEST BUXTON, ME. 

Abstracted from The Engineering Record oj July 27, 1907. 

There has been installed at West Buxton, about 20 miles west 
of Portland, Me., a 3,000-K.W. plant for the transmission of a three- 
phase, 60-cycle, 30,000-volt current to the Electric Lighting Com- 
pany at Portland. It will be operated by hydraulic power devel- 




Fig. 81. — Dam and Power-house. 

oped in the Saco River and involves the construction of a dam about 
300 ft. long, 33 ft. in extreme height, and 28 ft. in width at the base, 
a 100 X 100-ft. power-house, a 40 X 100-ft. dynamo-house with 
four 750-K.W. units, turbines and other machinery required, a 150-ft. 
boom, a log chute, and a 50 X 300-ft. tail race. 

At the site the river has a width of 350 ft., an average depth of 
3 ft., and a velocity of about 6 ft. per sec. at ordinary stages of the 
water. A 4- span highway bridge formerly crossed the river about 
100 ft. below the present dam and slightly oblique to it, a crib dam 



WEST BUXTON PLANT 



I6 5 



crossed the river about 50 ft. above it and connected at the east end 
with an old grist-mill and other buildings which occupied the site 
of the power-house. 

The dam is approximately perpendicular to the shore line and 




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l66 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

nas a standard cross-section with curved crest and ogee face down- 
stream, a vertical face upstream, and a depressed footing or cut- 
off wall at both the up and downstream longitudinal edges of the 
foundation. The west end of the dam makes an oblique angle with 
a concrete abutting wall which it intersects and with which it is 
integral ; the footings of this wall are carried down to rock and it 
has a maximum height of 10 ft. with a top width of 3 ft. It ex- 
tends about 100 ft. upstream from the dam to intersections with the 
maximum flow lines of the impounded water and is carried up to a 
height of 8 ft. above the crest of the dam, thus concentrating all 
flow over the crest of the dam and protecting the bank on the down- 
stream side. The wall was built in an open cut with 1 : 1 slopes 
and was back-filled on the shore side, the river side being left un- 
filled and excavated near the dam to a depth of 3 ft. below the crest. 
At the opposite end of the dam a sluice 11 ft. wide and 2 ft. deep 
below the crest is built to afford a runway chute for logs, and slopes 
rapidly downward to a point about 10 ft. beyond the lower face 
of the dam where it is below water-level. The sluice is integral 
on the river side with the dam and on the shore side with the outer 
wall of the power-house foundations. Normally, the sluice is 
opened, and the water discharged through it somewhat reduces the 
depth on the crest of the dam, but provision is made for closing it 
if necessary by stop planks fitting recesses in the side walls near the 
upper end. 

The power-house foundations are of concrete up to a level 7.5 
ft. above the dynamo floor, above which the structure is entirely 
of brick and steel except on the side toward the turbine chambers, 
which are separated from the dynamo room by a concrete wall 
extending 8 ft. above the crest. The floor of the dynamo room is 
13 ft. below the crest of the dam; and in order to provide for a 
possible flood such as was caused by an ice gorge eight years ago, 
the windows and doors are 7 J ft. above the floor, and the walls are 
made reasonably tight up to that height. Water is. admitted to the 
turbine chambers through five rectangular 16 X 16-ft. openings 
between the four longitudinal interior foundation walls which are 



WEST BUXTON PLANT 



167 



extended about 23 ft. beyond the intake gate to form piers with 
slightly inclined cutwaters and which rest on a concrete founda- 
tion on the solid rock 22 ft. below the crest of the dam. The piers 
support on their upstream 
faces a continuous rein- 
forced concrete girder with 
an irregular cross- section 
about 8 ft. deep and 7 ft. 
wide, having its lower sur- 
face 2 ft. below the crest of 
the dam to form a sort of 
boom to intercept any 
floating material and also 
a support for needles for 
closing any penstock above 
the gates, as well as mak- 
ing foundations for a fu- 
ture house over gates, 
hoists, and screens. A de- 
pressed walk 2 J ft. wide 
and 3 ft. above the crest of 
the dam provides a plat- 
form from which it is easv 
to push the debris along 
the face of the boom and 
from which needles may 
be placed. About 7 ft. in 
the clear, downstream from 
this girder there is a second 
thin horizontal girder sup- 
ported on the piers and 
extending across the full 
width of the power-house. It has a horizontal and inclined sur- 
face forming the bottom and one side of a trough opening into the 
log chute. The downstream side of the trough is vertical and is 




1 68 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

formed by horizontal planks separating it from the gates. The up- 
stream edge of the trough is at the level of the dam crest and forms 
a support for the inclined rack-bars 23 ft. 3 in. long and 2 in. apart 
on centres. The feet of these bars take bearings on a concrete footing 




w 

w 

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PM 

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t1- 

00 

6 



WEST BUXTON PLANT 1 69 

and they are intermediately supported by three lines of equidistant 
horizontal I-beams. A timber platform is carried by transverse 
I-beams 4 ft. above the top of the trough and permits an attendant 
easily to float the ice which may accumulate against the masonry 
or rack over the edge of the trough and thence push it or allow the 
current in the trough to carry it down to the log sluice. 

The floor of the turbine room is made with massive concrete 
arches without reinforcement which are 2.5 ft. thick at the crown 
and are carried by the 3 -ft. longitudinal interior walls in the plane 
of the outside piers above mentioned. The tops of these walls 
are pitched both ways from the centres to the springing line so as 
to give radial surfaces for the skewback bearings. The footings 
of these walls are carried down 39 ft. below the crest of the dam, or 
1 ft. below the level of the main excavation. The roof over the 
turbine room is similar in construction to its floor, but the arches 
are only 1 ft. thick at the crown and are pierced over the centres 
of the turbines with large circular holes closed with doors made 
with two crossed courses of planks. This floor forms an open plat- 
form between the front wall of the dynamo-house and the gate-hoist 
foundation which is a hollow concrete parapet 6 ft. wide and 7 ft. 
high. 

The entire area of the dynamo room is commanded by a travel- 
ling crane of 34 J ft. span, and 15 tons capacity, with its rails 5 ft. 
clear of the lower ends of the roof beams. These latter are 20-in. 
deep, spaced 7 ft. 8 in. apart on centres and are pitched about 1 in 
36. They carry a continuous 4-in. slab of concrete, reinforced by 
No. 10 expanded metal with 3 -in. meshes which is covered with 
tar and gravel. 

The intakes are closed by vertical wooden gates made of 4-in. 
horizontal planks with pairs of 8 X 10-in. vertical lifting beams 
bolted, keyed, and X-braced to them and provided with cast-iron 
racks engaging pinions operated by hand from the deck above. 
Many logs are run down the river and are diverted from the power- 
house by the main boom which extends from the log sluice to the 
river bank at a point about no ft. upstream, thus making an angle 



170 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

of about forty-five degrees with the face of the power-house and 
facilitating the movement of logs and other drifting material to the 
sluice. It is a horizontal concrete girder with a T-shaped cross- 
section 8 ft. deep and 5 ft. wide with vertical and horizontal webs 
respectively 2 ft. and 1 ft. in thickness. The vertical web is rein- 
forced by 19 rods with areas of 1 sq. in. spaced 5 in. apart, lapped 
2 ft. at joints and located 2 in. from the downstream face of; the 
beam. The horizontal web is reinforced by six bars each with an 
area of .62 sq. in. spaced 6 in. apart, lapped 13 in. at joints and 
located 2 in. above its lower surface and forms a walk. The booms 
are supported on concrete piers 4 ft. thick, with both sides bat- 
tered 4 : 1 and nearly 23 ft. apart on centres. The girder is made 
continuous with three-panel lengths and butt joints for expansion 
on the centre line of the centre pier, the river abutment, and the 
last pier at the shore side. 

The existing dam, over 100 years old, was made with cribs filled 
with stone, and, although in excellent preservation, was so leaky that 
all the silt and sediment had washed through it from the pond above. 
It was made tight with sand bags put in place by divers, and the 
crest was raised 5 ft. with flash boards supported on triangular 
wooden frames, the west end being torn out to take the flow. A 
low earth dam or dike, sheeted on the lower side, was built nearly 
across the river below the site of the new dam, and the river diverted 
to a channel near the west bank by a cofferdam 200 ft. long on the 
east side of the channel parallel to the shore line and connecting 
the old dam and the dike below. It was made with timber cribs 
15 ft. high, 12 ft. long, and 16 ft. wide floated to place, filled with 
sand, and sheeted with 3-in. tongue-and-groove vertical planks. 
The area between the dams was drained and kept dry with a single 
pulsometer and a 6-in. steam pump. The surface of the granite 
rock was found smooth and regular, but, on account of the deep 
seams it contained, was excavated with steam drills and dynamite 
to a depth of 4 to 8 ft. for the footings of the new dam. 

A concrete platform 33 ft. above the river bottom was built 
on falsework trestle bents at the level of the highway on the east 




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172 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

bank of the river. Stone from the excavation was broken and 
stored in a 1,000-yd. pile on the opposite side of the road from the 
platform, where sand and gravel were also delivered by wagons. 
Cement was stored in adjacent buildings, and all of the material was 
delivered by wheel-barrows to the centre of the platform, where 
they were measured and chuted through trap-doors to two mixers 
under the platform which delivered the concrete to i-yd. bottom- 
dump steel buckets on flat cars on a 2 -ft. track on a service platform 
about 400 ft. long and 16 ft. above the bottom of the river. The 
concrete was delivered to six guyed derricks with 5 -ton, 60-ft. 
booms which commanded the entire length of the dam and handled 
the forms and all materials. They were operated by double drum 
engines and handled a maximum of about 200 yds. of concrete daily. 

The concreting was carried on without interruption during 
the coldest weather and when the temperature was as low as minus 
47 . The only precautions taken were to mix the concrete with 
hot water and to soak the broken stone in a hot-water tank large 
enough for two i-yd. skips and heated by exhaust steam from the 
steam-engine and live steam from the hoisting-engine boilers. 
Although the sand was used cold, the concrete was so hot when 
first mixed that sometimes the men could scarcely walk in it with 
rubber boots. It was covered at night with tarpaulins and in the 
morning was found still moist and unfrozen. 

The dam was made in alternate sections 40 ft. long, bonded 
together with four vertical triangular 12 X 12-in. keys 18 in. apart in 
the clear. They terminated 2 ft. below the upper surface of the dam. 

Derrick stones up to 1 yd. in volume were bedded in the con- 
crete and formed about 30 per cent, of its mass. Care was taken 
in filling the moulds to complete a horizontal course over the whole 
surface each day, a requirement which necessitated the men some- 
times working from 12 to 14 hours; corresponding heights of from 
3 to 8 ft. a day were secured according to whether the work was at 
the base or the top of the dam. Successive courses were bonded 
together by large stones embedded in the surface so as to project 
half-way above the top of the lower course and tooth with the upper 



WEST BUXTON PLANT 



173 



course. The forms were built of 2 -in. square-edged dressed pine 
planks and were not interchangeable, being knocked down as each 
one was stripped and rebuilt for the next. 

The main generators are of the revolving-field type and are 



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1 



Fig. 86. — Switchboard. 



174 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

designed to carry an overload of 25 per cent for two hours without 
excessive overheating. They have a full-load efficiency of 94 per 
cent, and an efficiency of 91 per cent, at half load. 

The switchboard and transformers, in two banks of three each, 
are arranged in a row opposite the generating machinery. The 
transformers are rated at 500 K.W., and are oil-insulated and 
water-cooled. The cooling water is circulated through a coil in 
the upper part of the transformer tank over the core and surround- 
ing the ends of the windings. The water is taken from the fore- 
bay, near the exciter turbines, and carried beneath the floor in two 
3-in. pipes, which are connected by a third 3-in. pipe running cross- 
wise under the transformers. This cross pipe is connected with 
another lateral pipe lying close to the transformers, by risers in 
which are placed suitable screens. One-inch pipes lead directly 
to the respective transformers from the secondary lateral pipe. 
A glass is provided in the water circuit of each transformer so that 
the circulation is always under observation. From the transform- 
ers the discharge pipes lead downward into the tail-race. 

The switchboard and apparatus are designed for a current 
capacity commensurate with the 2 2, 000- volt transmission press- 
ure, and automatically operated oil switches are used on the out- 
going lines. There are nine principal panels as follows : One ex- 
citer panel, one regulator panel, four three-phase generator panels, 
one transformer panel, and two outgoing line panels. 

The design of the West Buxton plant, and in particular the 
transmission system, is based on the purpose of ultimately unit- 
ing the service with that of the Great Falls water-power plant 
at a main transformer station in Portland. The transmission 
lines from the Great Falls plant are to be carried direct to the 
new station. This will permit the abandonment of several sub- 
stations and auxiliary plants. The high-tension current from both 
West Buxton and Great Falls will be reduced to a uniform pressure 
of 2,300 volts for transmission to the Consolidated Electric Light 
Company's plant. There, motor-generator sets are placed for 
converting the united output to direct current at 250 volts, which 



WEST BUXTON PLANT 



J 75 



is distributed by a three-wire system throughout the business sec- 
tion of the city. At present there are installed at the main trans- 
former station mentioned six 500-K.W., 22,000/ 2, 300-volt self- 
cooled units, with provision for further transformer equipment to 
handle the Great Falls output. 

The transmission line from the West Buxton plant to Portland 
consists of two three-phase circuits of No. 2 wire, a metallic tele- 




Fig. 87. — Transmission Line. 



phone circuit of No. 12 copper wire, and a ground circuit of No. 
12 phono-electric wire. The main-line insulators are triple petti- 
coated glazed porcelain, and are mounted on hard maple pins. 
The circuits are carried one on either side of the pole on two cross- 
arms, and the triangles are inverted. The wires are placed 36 
ins. apart. The telephone wires are carried on brackets below the 
lower arm, while the ground wire is run over the tops of the poles 



176 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

and grounded at every sixth pole through a No. 4 B. & S. copper 
wire, connected by a brass screw-plug with a galvanized-iron pipe 
driven 6 ft. in the ground. The cross-arms are of long-leaf yellow 
pine, and are doubled at points of curvature on the line. The poles 
are " butt-cut" chestnut and vary from 35 ft. to 60 ft. in length, 
having a minimum diameter at the top of 8 ins. The spacing is 
100 ft. on tangents. 



THE HYDRAULIC POWER DEVELOPMENT OF THE 
ANIMAS POWER AND WATER COMPANY. 

Abstracted from The Engineering Record oj April 14, 1906. 

The Animas Power and Water Company was incorporated in 
Colorado for the purpose of building irrigation canals, reservoirs, 
and developing water power. The first work of importance under- 
taken by the company was the building of the Animas power plant, 
which is located on the Animas River and a branch of the Den- 
ver & Rio Grande Railroad, about half way between Durango and 
Silverton, just above the Animas Canyon. 

The power-house is a 108 X 64 foot brick and concrete building 
with a roof of steel and concrete, making it as nearly fireproof as 
possible. The building was erected to accommodate four units, 
only two of which are at present installed. The others are to be 
put in later. The leading features of the building are shown in 
the cross-section and photograph (see Figs. 91 and 92). The com- 
pany has at present contracts for more than 4,000 H.P. 

The power »is derived from water taken from Cascade Creek 
and the watershed tributary to the large reservoir. Cascade Creek 
has a flow of 3,720 cubic feet per minute and the watershed of the 
reservoir has 1,500 cubic feet more, making a total available water 
supply of 5,220 cubic feet per minute. The water is diverted from 
the creek and runs through a wooden flume 3 J miles long, which 
is 6 X 8 feet and laid on a grade of 0.2 per cent. From the flume 



ANIMAS PLANT 



177 



water flows into a natural water-course and empties into a reservoir, 
which has an area of 960 acres. 

The reservoir was made by building a stone-and-timber dam 
about 750 feet long and 55 feet high, with a foundation 33 feet deep 
to bedrock. It is proposed to replace this dam by one of con- 
crete 100 feet high and about 1,400 feet long. This will increase 
the area of the reservoir to 1,161 acres. When the concrete dam 




Fig. 88. — Animas Dam. 

is built, the company expects to take the water from Lime Creek 
into the reservoir, which can be done by building another flume 4 
miles long. When the water from Lime Creek is added, the avail- 
able water supply will be double, or 10,440 cubic feet per minute. 
At some future time, as the demand for power increases, it is pro- 
posed to use the water from the Animas River. In order to accom- 
plish this, it will be necessary to build a tunnel 8 miles long, and 
when this is done there will be sufficient water for developing 
some 38,000 H.P. 

From the reservoir the water is taken in a 38 X 56 inches 

wooden flume 8,800 feet long, laid on a grade of 0.25 per cent., 

which empties into an intake reservoir. The intake reservoir 

has an area of about five acres. Its dam is of earth, with a 

12 



I78 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

concrete core wall 3 feet thick and another concrete wall at the 
inner toe. At present it is 30 feet high by about 100 feet long, but 
it is to be raised 10 feet, which will give an effective head of 970 
feet at the power-house. 

The pipe enters the intake reservoir 25 feet below the surface 
of the water, thereby avoiding any possibility of ice entering or 
blocking the pipe. In front of the pipe is located the usual 
screen made of flat bars of steel. The end of the pipe is tapered 
to 60 inches in diameter; where it emerges from the dam it is 44 




Fig. 89. — Animas Flume. 

inches, and has a gate valve and a 10-inch standpipe on the lower 
side to admit air, so as to prevent any danger of collapsing the 
pipe in case the valve is rapidly closed. The standpipe passes 
through the gate-house and is enclosed in a wood flue. The heat 
from a stove in the gate-house passes through the flue and around 
the standpipe to prevent the water in it from freezing. 

It would appear that nature had intentionally left an opening 
in the cliffs for a pipe line to come down from this reservoir to the 
power-house. Starting at the top, where the elevation is 987 feet 



ANIMAS PLANT 1 79 

above the station, the pipe is 44 inches in diameter by 3-16 in. thick 
and runs for some 800 feet, on a slight grade over the mountain to 
a point where the head is 125 feet and the pipe is thickened to \ 
inches. From this point downward the metal in the pipe increases 




Fig. 90. — Pipe Line and Power-house. 

in thickness to 11-16 inches and the diameter changes to 40, 36, 
and 34 inches, there being an equal quantity of each diameter. 
The pipe is 2,842 feet long and is double riveted in the longitudinal 
seams and single riveted in the girth seams, down to 560 feet head. 



l8o DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

From this point it is double riveted in the longitudinal seams and 
single butt- strapped and single riveted in the girth seams down 
to a point where the head is 975 feet, and from there to the bottom 
the pipe is double butt-strapped and triple riveted in the longi- 
tudinal seams. The riveted joint efficiency is 82 per cent. The 
pipe is made up in sections 30 feet long and fitted with welded steel 
angle flanges. The flanges are bolted together with combination 
copper and lead gaskets between them. The gaskets are made 
with one ring of J-inch copper wire just inside of the bolts, then 
comes a lead ring 3-16 inches thick, and inside of this a 5-16 inch 
lead ring. The three rings are held together in places by solder 
and make a very substantial and perfectly water-tight joint. The 
heaviest sections of pipe weigh six tons each. The steepest grade 
on the line is 84 per cent. 

At the power-house and lower bends the pipe is thoroughly 
anchored in large blocks of concrete, each of sufficient size to carry 
the weight of the pipe above it. The sections of pipe at the 
lower end were tested to 650 pounds per square inch before 
leaving the shops of the company, which furnished the piping 
and water-wheels. The pipe was hauled up the hill with a mine 
hoist and cable, and the grade was so steep the cable could not be 
loosened from a section until it was in place. 

At the lower end of the pipe line there is a cast-steel Y, taper- 
ing down to two 20-inch branches fitted with gate valves having 
by-passes, and roller bearings connecting to the 20-inch by-pass 
needle nozzles of the wheels. The nozzles are arranged with a 
system of toggle levers by means of which the water can be turned 
from the wheel through the by-pass. These toggles are arranged 
so that, for a uniform rotation of the governor shaft, the variation 
in power delivered to the wheel will be constant. The by-pass is 
used in order to prevent shock to the pipe in case the load is sud- 
denly thrown off the generator. The needle which controls the 
supply of water to the wheel and the one to the by-pass are connected 
by means of a right-and-left-hand screw so that their relative posi- 
tions can be changed at will by means of a hand wheel. This hand 



ANIMAS PLANT 



181 



wheel can be set by the aid of a predetermined load curve and re- 
duces the waste from the by-pass water to a minimum. 

The wheels are 8 feet overhung Pelton wheels one on each 
generator shaft, with a normal capacity of 3,000 H.P. each at 
300 r.p.m., but capable of being run up to 4,000 H.P. The wheel 
centres and the buckets are made of cast steel. Each bucket is 
bolted to the wheel centre with one 2j-inch and one if-inch bolt, 
giving ample strength to permit the wheel being locked and full 




Fig. 91. — 3,000 H.P. Pelton Wheels and Generators. 



stream turned on or allowed to run as fast as the water will drive 
it with no load on. The shafts are fourteen inches in diameter at 
the bearings and 16 inches at the rotors or fields. They are hollow, 
with 5-inch holes through which water is made to circulate to 
assist in keeping the bearings cool. The bearings are 14 X 42 
inch water-cooled, and are babbitted in lower half only. 

The wheels are controlled by oil-pressure governors with two 
pumps, arranged so that one can furnish power for either or both 
governors. 

The generators are of 2,250 K.W.-capacity, and of the revolvmg- 
field, three-phase, 60-cycle type, with the exciter armature mounted 
on the shaft. The generator voltage is 4,000, with step-up trans- 
formers and line voltage of 50,000. 



1 82 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

There are six water-cooled oil transformers of 750-K.W. 
capacity each. Each transformer is located in an iron-and-con- 
crete vault, completely closed, so that in case of fire the oil cannot 
burn and damage any of the other apparatus. 

The switchboard gallery is located over the transformer vaults. 




Fig. 92. — Cross-section of Power-house. 

The generator mains run up through brick chambers to the oil 
switches and circuit breakers and then to the generator bus-bars. 
From the bus-bars the circuit passes down to the transformers 
where the current is stepped up to 50,000 volts. The circuits then 
go to the high-tension oil switches and circuit breakers, and from 
there to the transmission line. The switchboard is located near 
the front of the gallery and fitted with the usual instruments, to- 
gether with a voltage regulator. The operator in front of the 
switchboard has all of the machinery in full view. 

The transmission line is built of three cables, each composed 
of six No. 8 B. & S. aluminum wires with a hemp core and a con- 
ductivity equal to No. 2 B. & S. copper. The cables are arranged 



DRAMMEN PLANT 1 83 

on the cross-arms so as to form a triangle with 6-feet sides. The 
poles are pine, 36 feet long, and set 6-feet in the ground 250 feet 
apart. The longest span is 1,100 feet, where the cables stretch 
between wooden towers and span an arm of the reservoir. There 
is a substation in Silverton with transformers for stepping down 
to 17,000 volts. 



HYDRO-ELECTRIC PLANT OF THE CITY OF 
DRAMMEN, NORWAY. 

Abstracted jrom the Electrical Review of May 12, 1906. 

For supplying light and power to the city of Drammen and the 
surrounding country on the Drammen Fjord, located some twenty 
miles southwest from Christiania, the water of the Storelven was 
dammed at the waterfall " Gravfos" and utilized in the power-house 
located at the junction of the Storelven (the upper part of the river 
Draven) and the Suaramselven, some twenty miles above the city 
of Drammen. Preliminary to the construction of the power plant 
it was necessary to build a branch of the Drammen-Randsfjord 
Railway from Gjeithus and connecting from the end of this branch 
to the plant by way of a steel bridge over the " Gravfos. " 

About 65 metres (215 feet) above this fall a concrete dam 
is constructed, with the intake canal at the left of the river- 
bed, provided with six main sluice gates operated from a gallery 
above the intake. Connecting with this canal is a tunnel 230 feet 
long and 10 metres (32.8 feet) wide at the bottom with an arched 
roof cut in the mountain. On account of the softness of the rock 
it was found necessary to line this tunnel for a distance of 27 
metres (88 J feet) with brick. This tunnel leads into the col- 
lecting basin, which it was also found necessary to line with 
masonry. The tunnel enters one side of the collecting basin, 
while on the opposite side are two pressure tunnels, there being 
space for a third one. One of the ends of the basin is provided 
with an overflow and sluice gate to drain the basin in case of an 



184 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

emergency. All sand and gravel carried down to the basin is re- 
moved by a sand trap through the overflow channel. The sand- 
trap gates and also the emergency gates are operated from a point 
on top of the wall of the basin. Sluice gates are installed in the 
pressure tunnels, only one of which is at present in use. These 
tunnels are 4 metres (13.12 feet) high and 4.25 metres (13.94 
feet) wide and are lined with masonry. Two turbines are con- 
nected to this tunnel by means of two short steel branch penstocks, 
leading from one main penstock, and a third branch penstock 
leads to the two exciter units. 

As the available water supply was 30 cu. meters (1056 cubic feet) 





f ^kt- : ** < t\ ■ ■ hSv^^X^ 






' 


il • 1 4 * * jifr* 


1 11 H iL&lf 


i 


j * £^$ ;; flBig4^t* 


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r- ? ; : '". 


^^^^^^^^^^^^^T3**S"*^E35^^^^Bww^B^KJBftB[ 




- - 






....■..■■■.■■.. 




. .- ■ 
■,Jmm*' 



Fig. 93. — Power-house. 



per second with a net fall of 14.5 metres (47.5 feet), a development of 
4,400 H.P. was possible. This energy had to be transmitted over a 
distance of 35 kilometres (21 miles) and distributed to two harbor 
cities spread along the shores of the fjord. The plant was designed 
to generate three-phase alternating current at a potential of 5,000 
volts, which is stepped up to 20,000 volts and then transmitted to the 



DRAMMEN PLANT 



185 



city entrance of Drammen, where this secondary current at 18,000 
volts is transformed down to 4,500 volts. From here the current 
is distributed to a number of smaller transformer substations, 
where this 4,500 volts is again stepped down to 220 volts, at which 




'Fig. 94. — Plan of Power-house. 

potential the consumers are supplied. The feeder systems are 
installed partly overhead and partly underground. From the fore- 
going it will be seen that the installation includes a generating sta- 
tion, a step-up transformer system, a long-distance high-tension 
transmission line, a step-down transformer station, a high-tension 
distributing system, step-down transformer substations and low- 
tension distributing systems. The hydraulic plant is designed 
for four main units and three exciter units, having at one end 
space for the switchboard and step-up transformers. The total 
length of the plant is 42 metres (137.7 f eet ) an< ^ tne width 16 
metres (52.4 feet) with an extension on one side containing 
offices, storerooms, pump-room, and a repair shop. The entire 
building up to the generating-room floor is of concrete, while 
the upper part is of brick. The roof trusses are of steel covered 
with wooden planking and corrugated steel. A 50-ton overhead 
crane travels the length of the generating-room, but not over the 



1 86 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

switchboard. As already stated, the plant is designed to accom- 
modate four main units, although only two 900-H.P. units are at 
present installed and two 66-H.P. exciter units. 

Before entering the building the penstock is divided into two 
parts, each of 2.1 metres (6.88 feet) diameter, each supplying one 
of the main 900-H.P. units. In addition to these there is another 
third branch 1 metre (3.28 feet) in diameter supplying the ex- 
citer units. Each of the main pipes is equipped with a butterfly 
valve. To operate these butterfly valves electric motors are in- 
stalled in the pump-room, while the valve of the exciter penstock 
is operated by hand. The main turbines are built on the double- 
wheel Francis type, making, with a head of 14.5 metres (47.56 
feet) and 214 r.p.m., 900 effective H.P. Each turbine unit is 




Fig. 95. — Longitudinal Section of Power-house. 



provided with a flywheel. Between the turbine and flywheels is 
a clutch coupling. Each turbine is well provided with hydraulic 
governing devices. For switching the turbines in multiple the 
operation of the governor is controlled from the switchboard by 
an electric motor mounted on the side of the governor. 



DRAMMEN PLANT 



187 



The pressure water needed for the governor is supplied by two 
7-H.P. electrically operated pumps installed in the above-men- 
tioned pump-room together with the necessary accumulator. 

The exciters are also driven by Francis turbines, but of the 
single-wheel type. These turbines are also equipped with fly- 




Fig. 9$. — Transverse Section of Power-house. 



wheels forming part of the coupling between the turbine and gener- 
ator. The couplings are not of the rigid type, but are insulated 
flexible couplings. These turbines are also equipped with hy- 
draulic regulating mechanism, but the pressure, however, is sup- 
plied by the head in the penstock, thus avoiding the necessity of 
pumps, as is the case with the main units. The small turbines, 
with maximum water supply, have an efficiency of 75 per cent, 
while the main units under the same conditions have the same 
efficiency- With 0.8 load the efficiency is 71 per cent and with 
0.6 load, 70 per cent. 

With a sudden decrease in load from full to no load the varia- 
tion in speed will not exceed 15 per cent, while with a variation of 
25 per cent in load the flywheel holds the variation in speed down 
to only 2 per cent. 



1 88 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

The alternators are of the Oerlikon type, 750 K.W., 5,000 volt 
three-phase, 50 cycles, and are coupled to the turbine shafts by 
means of insulated, flexible belt couplings. The magnet frame is in 
two parts, divided horizontally, with laminated poles bolted to 
the frame. At full load and power factor = 1 the efficiency is 94 
per cent, while with power factor = 0.8 the efficiency is 93 per 
cent. In decreasing from full load to no load the potential in- 
crease in the former case is 7 per cent and in the latter case 
15 per cent. The above figures allow for the energy of excita- 
tion, which at full load is 7 K.W. with power factor =1 and 13 
K.W. with power factor = 0.8. The maximum temperature in- 
crease after a 24-hour full-load run does not exceed 40 C. The 
64-K.W. exciter sets are no-volt, shunt- wound, direct-current- 
generators, each connected by a flexible coupling to the flywheel of 
its turbine shaft, as already mentioned, and operate at 650 r.p.m. 

From the generators to the switchboard, cables are laid in a 
tunnel below the floor, three, 70 sq. mm., iron-bound, lead-covered 
cables leading from each machine. 

The switchboard is placed on the end wall of the plant 
and is two stories high, the lower part on the generator-room- 
floor level being occupied with the transformers and rheostats, 
while the upper part is taken up with high-tension (20,000 and 
5,000 volt) fuses, switching devices, measuring instruments, etc. 
Above this is a small gallery where are located the bus-bars 
and horn lightning arresters. The switchboard is completely 
equipped with the most modern apparatus and the entire wiring 
layout made with a view to convenience, flexibility, and simplicity. 
The current from each generator is measured, and the total current 
supplied to the 5, 000- volt bus-bars again measured by recording 
instruments before feeding the step-up transformers. Current at 
20,000 volts is then led out over a line protected by two horn light- 
ning arresters, on each phase arranged in parallel, and also choke 
coils. In addition to this, a continuous flow of water prevents 
the potential from rising above 20,000 volts. If the potential ex- 
ceeds this amount it is grounded through the water. 



DRAMMEN PLANT 



189 



For switching the generators in parallel a voltmeter switch, a 
phase voltmeter, and synchronizing lamp are provided. A small 
regulating motor is controlled from the switchboard. 

The switchboard is designed to accommodate the complete 
installation, although at present the apparatus for only two units 



Horn Lightning 
Arrester 



5000 Volt 
Bus Bars 







Fig. 97. — Section through Transformer and Switch Room. 



I90 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

and the auxiliaries is installed. The board is made of white marble, 
mounted on an iron frame. 

The switch system for the transformers consists of two separate 
systems, one for 5,000 volts lying in the generator-room, and the 
other for 20,000 volts in the transformer-room. The transformers 
are mounted on wheels, so that they may be moved onto low 
platform cars and carried into the repair shop. An air duct ex- 
tends under the transformers for ventilation, with a motor-driven 
fan at the end. 

The feeder system is designed to transmit 1,800 H.P. with a 
drop in potential of 11 per cent. The length of the feeder 
system is about 21 miles and consists of three hard-drawn copper 
wires with a sectional area of 25 sq. mm. 

The common method of carrying these wires is on wooden poles 
having three cross-arms in order to carry six insulators for 
two systems. Three insulators only, are at present in place. 
They are so placed that each cross-arm has one insulator. This 
is done in order to allow a turn of one-third in the relative position 
of the feeders, which takes place once in three and one-half miles, 
so that in the whole run the cables are twisted twice. The poles 
are placed about 210 feet apart. In crossing streets, streams, etc., 
protective wire nets are placed under the feeders, so that a broken 
wire may not drop to the ground. 

Wooden poles are used throughout most of the run; lattice- 
work iron poles, however, are used in several cases. These poles 
are of the requisite height and are thoroughly creosoted and pro- 
tected by cast-iron caps. The wires are carried on delta-shaped 
brown porcelain insulators bolted to the cross-arms. The cross- 
arms are braced by angle irons. Below this high-tension, 20,000- volt 
system for a certain distance is carried the 5,000-volt feeder on 
porcelain insulators mounted on iron brackets. Twenty-six inches 
below these are placed the telephone lines. Ten sectional cut-outs 
are installed, enabling the operator to disconnect certain districts. 
At the crossing, over the railway, a roofed steel structure is pro- 
vided to carry the feeders. 



DRAMMEN PLANT 






191 



O 

TT 



* 



I * . [ 
7-500 1 



There is at present one transformer station for reducing the 
potential from 18,000 to 4,500 volts. On entering the station the 
wires are equipped with two parallel switches and horn lightning 
arresters for each phase. In connection with the arresters 
there is an induction coil in each phase. From the substation, 
three cables and one air line lead out at 
a potential of 4,500 volts for the high- 
tension distribution system. A small 
auxiliary transformer is installed to fur- 
nish power at 220 volts for lighting the 
station and to operate the transformer 
blower. As the transformer station is a 
three-story building; the main floor con- 
tains the transformers, blower, etc., the 
second floor the switching system for the 
outgoing feeders, and the third floor the 
lightning arresters for the incoming and 
outgoing feeders. The transformers are 
of the same design as in the main power- 
house. 

The high-tension distribution system 
leads to two transformer substations be- 
ing carried on the same poles as the 
high-tension transmission line. The 
wire is 20-sq. mm. hard-drawn copper, 
mounted on brownglazed porcelain in- 
sulators. The greater part of the high- 
potential distribution system is that 
carried underground on cables for about 
eight miles. From the substation two 

cables run to each of the two halves of the city on the opposite side 
of the river and fjord. These cables are paper-insulated in a lead 
sheathing, filled with jute, and iron bound. At the sub-transformer 
stations the potential is stepped down from 4,500 to 220 volts. 
There are altogether, 14 tiansformer stations, 12 of which are in 




Fig. 98. — Pole-head. 



I92 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

the form of cylindrical steel towers about 5 J feet ifi diameter and 
some 20 feet high, while the two others are of brick. The former 
stations rest upon solid concrete foundations and are provided with 
doors to give access to the different apparatus. Special care is taken 
for good air circulation; the air entering at the bottom rises and 
is discharged below the top hood. 

The high- and low-tension systems are, of course, distinctly 
separate, and so also are the light and power systems. In order 
to simplify the wiring as much as possible, the three high-tension 
bus-bars, which are of aluminum, are mounted directly on the fuses. 
On the low-tension side, the feeders run down to a three-pole knife 
switch and to the fuses. Here, also, the bus-bars are mounted 
directly on the fuses. The iron frame of the stations as well as the 
transformer frames are positively grounded with a copper wire. 

The masonry buildings are made of rough stone and well sup- 
plied with natural light and also designed for air circulation. The 
wires of the 4, 500- volt system enter the station through glass plates, 
passing through induction spools and fuses to the transformers. 
The system is protected by three, horn lightning arresters. The 
other equipment is the same as for the iron towers. 

The low-tension distributing system consists of overhead air 
lines and underground cables, the latter being laid in trenches 
28 inches deep and covered by tiling. The overhead lines do 
not run directly from the transformer stations, but are connected 
from the underground feeders, at which points, small iron lat- 
ticed poles are erected. These poles are surrounded by an iron 
sheathing 6J feet high, provided with a door to give access to the 
fuses, etc. From the fuses the feeders rise to the top of the pole, 
which is also surrounded by sheet iron behind which the induc- 
tion coils are arranged. The lightning arresters are installed out- 
side of this casing. The arresters and towers are grounded by a 
common copper wire. From these distributing towers the wires 
lead to the various consumers. 



GREAT FALLS PLANT I 93 

THE GREAT FALLS STATION OF THE SOUTHERN 

POWER COMPANY. 

Abstracted from the Engineering Record of May 18, 1907. 

The Southern Power Company owns or controls in all nine 
water-power sites in the so-called Piedmont Section, embracing the 
sand-hill district extending from the foot of the Blue Ridge moun- 
tains to the fall line, a distance averaging probably 120 miles. 
One capable of development for 12,000 H.P. lies on the Broad 
River of the Carolinas equidistant from Gaffney and Blacksburg, 
S. C, while another is located on the Wateree River, of which the 
Catawba River is the principal tributary. This one is capable of 
development for 20,000 H.P. All others are on the Catawba 
River. The aggregate of these powers will amount to 145,000 
H.P., which will be transmitted to cover a territory over 150 miles 
long and about 100 miles in width. 

The Great Falls. — The Great Falls of the Catawba consists of a 
series of falls and shoals having a total head of 176 feet in a distance 
of about 8 miles, the development of which will require three 
separate plants. 

The lowest of these necessitates the construction of a dam 
across the river just below the mouth of Rocky Creek, at which 
point there is available a drainage area of 4,450 square miles; 
a development of 60 feet is here feasible, which head backs 
water to the elevation of tail water in the middle development. 

The highest development with a drainage area of 3,900 square 
miles will be effected by the construction of a dam immediately 
above the mouth of Fishing Creek. This plant will operate under 
a head of 40 feet, and its tail-water elevation will correspond to 
head water for the middle development. 

The middle development with a head of 72 feet receives the 
run-off from the drainage area of 4,20c square miles, and is known 
as the Great Falls Station, the subject of this description. 

From observations made under various auspice's it has been 



194 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



deduced that although the minimum flow of the rivers in this particu- 
lar locality averages about J cubic foot per second per square mile 
of drainage area and for eight months in the year about f cubic 

foot may be depended 
upon, the flood volume 
against which precaution 
must be taken in design 
is somewhat below 50 
cubic feet per second per 
square mile, such flood- 
water flow being an ex- 
ceedingly high one, and, 
it is thought, the greatest 
on record with the U. S. 
Geological Survey. 

This development 
consists essentially of a 
low spillway dam at the 
head of Mountain Island 
to deflect the water into 
the western channel. 
Flowing through this 
channel nearly to the 
foot of the island, it is 
then forced through the 
head-gates of the canal 
<* by another spillway dam. 
An extension of this dam 
serves as an overflow 
weir between the canal 
and the river. From this 
point the stream is car- 
ried by a canal through 
a natural valley about 
1 \ miles to the power- 




GREAT FALLS PLANT 



195 



house and retaining bulkhead built across the valley, while below 
the power-house the tail-race carries off the spent waters J mile to 
Rocky Creek, in which channel it is again carried to the river-bed. 
Canal Head-works —-The deflecting dam at the head of Moun- 
tain Island is an ogee section overflow dam only 7 to 8 feet high, 




Fig. ico. — Diverting Dam and Canal Spillway. 



the fall utilized for this development occurring almost wholly in 
the western channel, and in the dip of the valley through which 
the canal is carried to Rocky Creek. 

The main spillway at the head-gate works, 438.85 feet long on 
the crest line with an average height of about 30 feet, has a batter 
of 1 : 10 on the upstream face and an ogee downstream face. The 
corresponding width at the base of the section is about 41 feet. 
This spillway, in connection with the diverting spillway at the head 
of Mountain Island is designed to carry safely a flood overflow 
corresponding to 50 cubic feet per second per square mile of drain- 



196 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

age area, which volume of flood water will cause overtopping of 
the crest of the dam to a depth of 14^ feet. 

The curve on the downstream face was determined by plotting 
the parabolic curve for the average velocity of the film of over- 
flowing water increased by an assumed initial velocity of eight miles 
per hour, and so fitting the masonry to this curve as to intercept 
the nappe, breaking the velocity near the top and thus insuring 
contact of the sheet of water on the entire downstream face. The 
weight of masonry was assumed to be 125 pounds per cubic foot. 
An upward pressure equal to two-thirds of the head at the heel of 
the section and decreasing to zero at the toe was assumed to exist, 
and there was also considered to offset this pressure the weight of the 
overflowing sheet of water tending to increase the stability of the 
dam. Under these assumptions the section shows a safety factor 
of two for the most severe conditions, with increasing stability as 
the conditions approach the normal stage. 

The spillway in the canal, similarly designed, and 521.2 feet 
long on the crest, averages about 36 feet in height, corresponding 
to which height the base has a width of about 37 feet 9 inches. 
The crest of this weir is one foot higher than that of the main 
spillway and its length is such that, with the worst conditions of 
flood that may be predicted, it will, when overtopped to a depth 
of 8 feet, carry off all the water that the canal head-gates will 
vent. 

These spillways, the head-gate masonry, and all heavy bulkheads 
were built of concrete masonry, in which are embedded displace- 
ment stones as large as could be handled by the derricks. All 
masonry is founded on bed granite of a close and uniform texture. 
Sectional forms were used to the greatest practicable height, the 
upper curve being then finished by hand and template. 

The concrete was mixed largely in the proportions of one part 
of Edison Portland cement to two parts of sharp, creek sand ob- 
tained on the building site and five parts of crushed granite, the 
run of the crusher having been used throughout. 

The head-gate masonry supports a set of coarse racks and has 



GREAT FALLS PLANT 



197 



in it ten ways 16 feet wide and 18 J feet high with full- centred arch 
tops. These gate openings are separated by piers 5 feet in width. 
This section, averaging about 45 feet in height, is 8 feet wide on 
top, and the downstream side is battered 3 on 1. The piers are 
extended on the downstream side to form buttresses, which are 
5 feet wide, 3 feet long on a level with the top of the main wall, and 




Fig. ioi. — Section of Spillway of Main Dam. 



battered 2 on 1. Piers are also carried out on the upstream side 
for the support of the rack structure. These are 3 J feet long on 
top, this being 6 feet below the top of the main wall, and are bat- 
tered 12 to 5, giving for the section a total width at the base of the 
gate opening of about 47 feet. 

The gate frames secured into this masonry are built of standard 
structural steel shapes. They are of the same dimensions as those 
used for the gates of the turbine intake flumes, and it was contem- 
plated using the turbine head-gates in these frames for construction 



I98 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

purposes. Temporary gates were, however, later built of timber 
for this purpose. 

In the event of placing gates in these frames it might become 
necessary to relieve the pressure upon them before raising, and for 
that purpose a by-pass has been built through this masonry at 
the shore end. The gate is of timber and is operated by a 
Smith gate hoist. 

For the purpose of draining the low point immediately below 
these gates, a 4 X 5-foot sluice gate was built into the bulkhead, 
discharging below the spillway. 

The racks protecting these waterways are coarse, being built 
up of §- inch grid-bars, 5 inches deep, spaced 3 inches centre to centre, 
and separated by cast-iron spacers of such design as to prevent 
twisting of the bars under shock. These grid-bars are supported 
by a structural steel frame which in turn is supported by steel 
members built into the rack piers. This entire rack structure 
was designed of such strength as to withstand any pressures that 
might occur with a full head of water against a completely clogged 
rack. The racks were set on a batter of 12 to 5, so that logs and 
debris that might lodge against them should be forced to the top, 
whence they might be piked to a sluiceway 3 feet deep and 8 feet 
wide left in the spillway section for that purpose. There have been 
left in this sluiceway grooves for the accommodation of stop-planks 
should such economy of water become necessary. 

Construction of Head-works and Canal. — The method employed 
in the prosecution of this work was, in general, as follows : Coffer- 
dam No. 1 was built deflecting all the water to the deeper channel. 
The block of masonry marked A was then built. These coffer- 
dams consisted of log cribs filled with stone and sheathed top and 
sides. The building of blocks B and C was then undertaken, 
whereupon cofferdam No. 2 was built, and when completed coffer- 
dam No. 3 was built. Then all the head-gates, except those in the 
last two frames, were closed, and cofferdam No. 1 was opened and 
the water was vented through sections E and F. Temporary gates 
were then placed in the vent E, but a flood at this time tore out 



GREAT FALLS PLANT 



199 



the gate pier, and necessitated the building of cofferdam No. 4, 
within which this closure was effected. The two remaining head- 
gates were then placed in the frames, and, temporary gates having 



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been placed in the frames of vent F, the final closure was made. 
In making the closure, section D, nearly 200 feet long and contain- 
ing about 6,000 yards of masonry, was built in nine days and nights. 



200 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

For carrying the water from this point to the power-house it 
was necessary to excavate but little material to secure a hydraulic 
grade line from the bottom of the canal gates to a point 4J feet 
lower at the power-house. 

Such excavation as was necessary to secure a cross-section with 
a base of 100 feet and side slopes in rock of 2 to 1 and in earth of 
1 to 2 amounted to but 195,000 cubic yards, for a total length 
7,250 feet, and all of this material was necessary for filling in a 
gap existing between the valley and the river. 

The site of the fill was prepared by clearing off all vegetable 
matter along a strip 100 feet wide, and on this strip a puddle of 
selected material was placed. 

Station Intakes.— At the lower end of the canal the water is 
impounded by a concrete retaining wall or bulkhead having a 
width on top of 8 feet, a vertical upstream face and a downstream 
face battered 1.75 to 1, the height in the centre of the valley being 
about 90 feet. This section is largely increased in that portion 
opposite the power-house, for here there are built through the bulk- 
head the intake flumes for the turbines, the cases of which are also 
built into this masonry, and the power-house is built immediately 
below the bulkhead, forming virtually a part of it. 

Through this masonry, carrying past either end of the power- 
house, there have also been constructed two trashways for by-pass- 
ing leaves and small debris from the racks. These are 48 inches in 
diameter, built of riveted steel pipe and closed by sluice valves. 
Into these, by a manhole and check valve, there is also carried storm 
water off the side slope of the valley. 

Before the water reaches the head-gates of the turbine intake 
it is against passed through a set of racks similar to those at the 
head of the canal, except that these are finer, the grid-bars con- 
sisting of J-inch bars 4 inches deep, spaced ij inches centre to 
centre. Provision has been made for the attachment of a power- 
operated rack-cleaning device, which will have to be installed a 
few years hence. 

After passing these racks the water is controlled in its passage 



GREAT FALLS PLANT 



20I 



to the turbines by structural- steel gates. Eight of these for the 
generating units are built of 6-inch I-beams, and are covered with 
f-inch steel plate on the outer side. On the inner side they have 
bronze running strips at the sides and opposite the supporting 




202 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

beams in the gate frame, while machined-steel bearing plates at 
top and bottom insure tightness when the gates are closed. Each 
of these gates is provided with two 9 X 14-inch filling gates for 
reducing the pressure before raising, these being hand-operated 
from the top of the bulkhead. The gates are suspended upon 
steel stems, each built up of an 8-inch, 18-pound I-beam, and a 
9-inch, 20-pound channel, and to the latter is secured the pinion 
rack engaging with the gate hoist. 

The gates are operated by a multiple spur and worm gear off 
a shaft actuated by a motor from a point in its middle. The motor 
is stationed in a small house on top of the bulkhead, the leads for 
it being carried in vitrified conduit to a switch box in the tunnel 
and thence to the switchboard. Speaking-tubes are carried from 
this house and also from various points in the transformer-house 
to the operator's desk in the power-house. On account of the great 
initial torque required, a direct-current compound-wound motor 
with a weak shunt field, operating from the exciter circuit at 250 
volts, was selected for this service. This is practicable since the 
exciter plant is of a capacity largely in excess of that required for 
the mere excitation of the generators. By the use of pin clutches 
it is possible to operate any or all gates at one time. The 
clutches must, of course, be thrown in while the shaft is at rest. 
Provision has also been made for operating any of the gates by 
hand. 

The two gates for the exciter intakes are similar to those just 
described, except that they are framed out of 4-inch I-beams, the 
stems being composed of a 6-inch 12 J pound I-beam and a 9-inch 
13 J-pound channel, and but one 9 X 12-inch filling-gate is provided. 
They are raised by hand-operated mechanism. All these gates 
slide in heavy frames built of structural-steel shapes anchored into 
the masonry of the bulkhead wall. Directly behind the gate frames, 
but not rigidly attached to them, commence the intake flumes or 
feeder pipes for the water-wheels. These are made of f-inch boiler 
plate stiffened by 6 X 3 J X f-inch angles riveted around it. These 
flumes taper down from the head-gates, where they are 16 feet wide 



GREAT FALLS PLANT 203 

by 18 J feet high with semicircular ends, to 16 feet in diameter at 
the mouthpiece of the turbine case. 

Turbines. — There are ten units, each consisting of a pair of 
horizontal twin turbines with top inlet and centre discharge. 
Eight of these are required to furnish 5,200 H.P. at 225 r.p.m. 
under a head of 72 feet. 

Of these units two are a pair of 48-inch wheels enclosed in a cast- 
iron wheel case mounted in a turbine case of 7-16-inch boiler plate 
riveted to cast-iron heads. The latter are stiffened against shocks 
by four 2j-inch Norway-iron rods extending from the front to the 
rear head. 

In the feeder pipe and over the centre of the turbine is a man- 
hole, just inside which is an eye-bolt for the suspension of blocks 
for handling turbine parts. Pressure and air vent pipes 12 inches 
in diameter run up through the bulkhead. 

The draft tubes are 8 feet 10 inches in diameter at the wheel 
case, being flared at the bottom to a width of 18 feet, the ends 
being semicircular and of 4 feet 5 inches radius. The top of the 
mouth is sprung to form an arch 2 inches high to prevent any 
possible collapse of the metal away from the masonry. These 
tubes are fabricated from 7-16-inch plate and are stiffened in the 
same manner as the intake flumes. 

The plates of the upper 1 2 feet of the draft tube from the saddle 
down are butt-jointed and strap-covered on the outside with coun- 
tersunk rivets on the inside. Below these plates the joints are tel- 
escopic, with the lap in the direction of the flow of water. In the 
heads of the turbine case are removable crown plates of such size 
as to permit removal of any part of the work inside the flumes. 

Should it become necessary, the turbine cases may be drained 
by valves operated from the power-house. Check valves, for re- 
moval of any water seeping into the power-house, are provided be- 
fore each unit in a sump, which extends the entire length and in 
front of all the wheel cases. 

Vacuum gauges are provided for all draft tubes. The draft 
head in these wheels is 22 feet, and the draft tubes are submerged 



204 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

5 feet, which depth was deemed necessary to permit drawing off 
the pond on the lower development. 

The runner of each wheel is of bronze and mounted on a 
shaft 30! feet long made of forged nickel-steel; it is 9, 10, and 11 
inches in diameter, with a flange coupling keyed to it for connec- 
tion to its generator. This shaft is supported on the outside of 
the turbine case by ring-oiling, ball-and-socket bearings, the one 
in the power-house being made to harmonize in appearance with 
the bearings of the generators. 

A special feature of this plant is the construction of a tunnel 
extending the length of the power-house through the bulkhead and 
just back of the turbine cases. By this method of construction the 
usual outboard water-bearing is replaced by an oil bearing which 
may be inspected at will, and the removal of water-wheel parts is 
also greatly facilitated. This tunnel is 10 feet in width and has a 
segmental arch top, in which is anchored an I-beam trolley for 
carrying material to and from the power-house, into which the tun- 
nel opens. Ventilation is here provided by three, 12-inch air flues 
to the top of the bulkhead. The water-wheel shaft extends into 
this tunnel through a cast-iron head similar to that in the power- 
house. 

The outer bearings are ring-oiling ball-and-socket bearings of 
the propeller type. The pedestal boxes are rigidly connected to 
the head, being designed to take up the end thrust of the water- 
wheels. The flow of water to these wheels is regulated by cylinder 
gates. All racks and pinions for the gatework are placed on the 
outside of the turbine case. Hand regulation is provided for these 
units separate from that of the governors. 

The guaranteed efficiency of each of these units is determined 
by a curve passing through the following points: 

Discharge Full I t f i 

Efficiency per cent 81 82 81 74 68 

Six of the larger units are set in a turbine case of 7-16-inch plate, 
15 feet in diameter and 19 feet long. In this case the cast-iron heads 
are stayed across the wheel case. The feeder pipe is 18 J X 16 



GREAT FALLS PLANT 205 

feet at the intake gates, and tapers to 1 5 feet in diameter at the mouth 
piece of the turbine case. 

The draft tubes are 1 1 feet in diameter at the base of the wheel 
case, and flare to 18 feet 3 inches by 11 feet 2 inches at the lower 
end. Two of these units are provided with bronze runners 53 
inches in diameter, and four have runners of special cast iron, the 
latter being guaranteed against failure or undue wear for a period 
of five years. The gates are of the register type, being nearly bal- 
anced, with, however, a tendency to close. 

The shaft is of forged steel 9, 11, and 13 inches in diameter, and 
has a flange coupling forged to its end for the generator connection. 
The guaranteed efficiency curve passes through the following 
points: 

Discharge Full f f f I i 

Efficiency per cent 80 81 82 80 78 60 

The two exciter units are similarly built. These were required 
to furnish 700 H.P. at 450 r.p.m. under 72 feet head. 

At the intake the feeder pipes are 9 feet high with semicircular 
ends of 3-foot radius, and taper to a diameter of 6 feet at the mouth- 
piece of the case. These pipes are equipped with manholes and 8- 
inch vent pipes. Runners are 24J inches in diameter, the shaft 5^- 
inches in diameter, and the draft head is 21 feet 2 inches. The 
draft tubes are 5 feet 6 inches in diameter at the case and flare to a 
width of 9 feet 10 inches with semicircular ends of 2 feet 9 inches 
radius. 

For facility in erection, the water-wheels were mounted on a 
long, heavy structure of I-beams to span the openings left in the 
masonry for the draft tubes extending from the arches of power- 
house substructure to the masonry built up outside the draft-tube 
clearances. It was proposed setting these with the cradles in 
place, rigidly suspending from them the draft tubes, and then 
filling in around them with concrete. However, owing to delayed 
deliveries of the cradles, the draft tubes were loosely suspended 
from temporary beams braced to position and concreted in, the 
connection with the cradle fitting very well. 



2o6 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

Regulation of this plant is effected by Lombard governors. 
The generators are governed in pairs, and for each pair a type 
N governor is provided, while both exciters are controlled by 
one type P governor. There are provided for this installation 
four 4 X 6-inch triplex pumps operated by a belt from the water- 
wheel shafts. All pressure and vacuum tanks are placed in the 
bearing tunnel and the entire system is interconnected. The 
type N governors developing 31,000 foot-pounds are guaranteed to 
completely open or close the water-wheel gates in ij sec, while 
the type P governor will close exciter gates in 4 sec, developing 
6,700 foot-pounds. The larger governors are electrically controlled 
from the switchboard. 

Power-house. — The generator turbines discharge into the tail- 
race between piers, which, being spanned by full centred arches, 
form the substructure of the power-house. These piers are 5 feet 
in width and 25 feet between centres, except where both exciter 
turbines discharge into the same bay, the piers forming this one 
being 30 feet between centres and bridged by an elliptical arch, 
giving the same rise as the full-centred arches. All piers and 
also the facing on exposed parts of the substructure were built 
out of very finely finished dimension stone, which was quarried 
out of lock? built in the early part of the last century by the State 
Government in an attempt at making the river navigable past the 
falls and shoals. By this means and by paving the bottom with 
concrete, these tail flumes were made quite smooth and present 
but little impediment to a rapid discharge of spent water. The 
piers for the three central bays are carried in a like manner down- 
stream from the power-house to form the substructure for the 
transformer-house, but here the span between piers is not bridged 
by an arch, except just at the lower end, where these arches carry 
the outside wall and were used largely for the sake of maintaining 
a uniformity in the external appearance of the structure. 

The power-house is 250 feet long and 37 feet wide; the 
transformer-house extending from this is practically, a three- 
storied building, 7 1 feet in width.and 85 feet long. These buildings, 



GREAT FALLS PLANT 207 

of fireproof construction, are faced on the outside with red pressed 
brick and on the inside with a gray sandlime brick, the body of 
which is granite dust. Weepers were built just back of the brick 
walls on the bulkhead side of the power-house, drainage from these 
leading to the sump in the power-house. The roof covering con- 
sists of tile resting directly on steel purlins supported by steel 
trusses. These tiles lay up 24 X 48 inches, and are built of con- 
crete reinforced by expanded metal and made interlocking. They 
have a water-proofing burned into the exposed surface. The 
roof of the transformer-house was designed with a wide overhang 
for the protection of the line openings. Proper ventilation was 
provided for by the use of very large windows with casement 
side sash, which may be widely opened. Windows were also 
placed above the crane track on the upstream side of the 
house. These windows are hinged on top, the entire gang being 
operated from two power sash-lifting devices at opposite ends 
of the power-house. By this means it is possible to close them 
readily in case of sudden shower when rain might blow in on the 
electrical machinery. Two 20-inch ventilators were placed in the 
roof over each bay, and a 48-inch slat ventilator was built into each 
end of the house. In both ends of the house are placed steel roll- 
ing doors with a clear opening of 16 X nh feet. 

A conduit for the accommodation of wires and pipe extends 
along the downstream side of the power-house, the top forming 
a platform 3 feet 9 inches above the floor line. This platform 
widens on a circular arch in the centre of the house, opposite the 
exciter, forming a dais for the mounting of switchboard and in- 
strument posts. A hand-operated travelling crane runs from one 
end to the other of the power-house. This has a capacity of 25 
tons, and is equipped with a drum on which is wound the plough- 
steel hoisting rope. The girders are built of reinforced I-beams, 
and on the lower flange of one of these -operates a 5-ton auxiliary 
trolley with triplex block. In the tunnel a 5-ton trolley is suspended 
from the crown of the arch on an I-beam track for the handling 
of wheel and bearing parts. 



208 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

The transformer-house, as already stated, is a two-storied struct- 
ure, the conduit floor or basement of which is practically on a level 
with the bottom of the cable conduit in the power-house. The 
skeleton of this floor consists of I-beams spanning the opening be- 
tween piers, the space between these beams being spanned by con- 
crete arches with a concrete covering protecting the lower flanges 
of the beams. The piers were carried full width through this floor. 
The floors of the first and second floor are similarly constructed 
except that curved corrugated steel sheets were supported on the 
lower flanges of the I-beams, and on these was placed the concrete. 
The first floor is on a level with the switchboard platform. It is 
divided into rooms for housing transformers over both side bays 
and extending the full length of the house, while that portion lying 
above the piers of the central bay forms a room for low-tension 
switching apparatus. Immediately back of the switch-room and 
overlooking the tail-race is an office for the operators. From the 
power-house, entrance is gained to those rooms in which the trans- 
formers are placed through arches protected by rolling steel fire 
doors with fusible links. A similar door divides these rooms into 
two separate compartments, so that any one bank of transformers 
will be automatically isolated from the others in case of fire. The 
second floor has no partitions in it whatever, forming thus a room 
of such size as to contain all the high-tension apparatus with a 
generous allowance for clearance between leads. All apparatus 
is taken up through trap doors located above the tracks for the 
transformer transfer carriage, thus making their handling a simple 
matter. A 36-inch ventilator in the roof will insure against ex- 
cessive temperatures in this room. 

THE HYDRO-ELECTRIC DEVELOPMENT AT TRENTON 

FALLS, N. Y. 

Abstracted from The Electrical World of May 19 1906. 

The waters of the Canada Lakes in the Adirondacks of New 
York State find their way to the Mohawk River through two streams 



TRENTON FALLS PLANT 209 

known as the East and West Canada Creeks. The former empties 
into the Mohawk at East Creek and the latter at Herkimer. The 
West Canada Creek is the larger, and near the village of Trenton 
Falls it has a descent of nearly 300 feet in less than a mile. It is 
at this place that the 8, coo H.P. hydro-electric station of the Utica 
Gas and Electric Company is located. 

The Dam. — The dam is a concrete structure of the gravity 
type, 300 feet long and 60 feet high, built across the Creek on the 
arc of a circle having a radius of 800 feet, at a point about three- 
quarters of a mile distant from the power-house. 

Eight 60-inch cast-iron pipes are built into the dam near the 
bottom, two of which supply the pipe line feeding the turbines 
now installed, two for the supply of a second pipe line when 
the power-house is extended, and four to assist the waste weirs 
in carrying off the excess water in times of extreme floods. All 
of the 60-inch pipes are equipped with cast-iron sluice-gates having 
bronze guides and are operated from the top of the dam. 

The flood-water weirs above-mentioned are two in number, 
one being built at right angles to the dam and close by it on a 
rock shelf on the east bank of the stream, the other forming a 
part of the dam proper. The first weir or spillway mentioned is 
160 feet long, the crest being 9 feet lower than the top of the coping 
on the dam. The second weir is 100 feet long and its crest is two 
feet higher than the crest of the former. 

By this construction, the waste of flood water in the reservoir 
will flow over the spillway first mentioned through a rock cut 
around the dam to the creek below until the water flowing over 
it is two feet in depth, when the spillway on the dam will come into 
action and both weirs will then carry the waste water. The first 
weir mentioned can be provided with flash-boards, so that the level 
of the water in the reservoir can be raised two feet during the dry 
season. 

Both the dam and the weir on the dam are capped with heavy 
stone coping securely held by dowel pins, while substantial stone 
wing walls are constructed on the downstream face of the dam 



2IO DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

to confine the flood water within the limits of the spillway and 
thereby protect the face of the dam from injury due to debris, 
etc., in time of floods. 

The Pipe Line.— -The conduit which conveys the water from 



Fig. 104. — Section through Bulkhead. 

the reservoir to the turbines in the power-house is 84 inches in 
diameter and about 3,700 feet long. It is connected to the two 
westerly 60-inch pipes in the dam by means of a 6c X 60 X 84-inch 
cast-iron Y piece and two 60-inch gate valves enclosed in a gate- 
house, the latter being used to control the flow of water in the pipe 
line. 



TRENTON FALLS PLANT 



211 



The long pipe is composed of wooden- 
stave and steel-plate pipe, the major por- 
tion of its length being constructed of 
Texas pine staves securely held in posi- 
tion by round-iron bands, and joined to 
the steel pipe 2,900 feet from the dam. 

Twenty wooden staves, each 2 J inches 
thick, sawed on radial lines, are used in 
forming the circumference of the 84-inch 
diameter circle, the lumber being the best 
of its kind that could be obtained. 

The steel pipe, which is about 800 
feet long, is built of plate varying from | 
to I inch in thickness, and thoroughly 
coated inside and out at the mill with hot 
asphalt pitch. All connections of plate 
are made with lapped joints, the cir- 
cumferential seams being single riveted, 
while the longitudinal seams are double- 
riveted. All pipe constructed of f-inch 
material is stiffened by means of angle 
irons. 

The wooden-stave pipe is built on a 
light descending grade, and it winds in 
and out along the west bank of the creek 
throughout its entire length. After its 
junction with the steel pipe, the grade 
becomes much greater and the pipe con- 
tinues in a straight line for several hun- 
dred feet to a standpipe 84 inches in di- 
ameter and about 200 feet in height, 
which is built into the supply conduit to 
relieve any pressure in the line caused by 
extreme load conditions. This standpipe, 
which is covered with shingled casing 



y 



JO 






% 



«H 



»«qo rc 



212 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 




having a well- shaped cu- 
pola at the top, is 20 feet 
higher than the dam. 

Just after passing the 
standpipe, the penstock 
descends along the cliff at 
a sharp angle to a reservoir 
near the power-house, 125 
feet below the top of the 
bank. The reservoir is 
anchored on concrete 
foundations just outside 
the west wall of the power- 
house. It is provided with 
four 48-inch outlets, each 
of which delivers water to 
a turbine wheel under a 
head of 266 feet. The 
flow of water to each tur- 
bine is controlled by a 48- 
inch gate valve, the ar- 
rangement being such that 
anv or all valves can be 
operated simultaneously 
by hand, or by power fur- 
nished by a Pelton water- 
wheel. 

The penstocks to the 
turbines, the pipe line, and 
receiver are all equipped 
with valves to assist in re- 
lieving any excess pressure 
which might come on 
them, and the main pipe 
line is provided with a 



TRENTON FALLS PLANT 213 

number of air inlet pipes to allow for the escape or intake of air 
when the line is being filled or emptied. 

Hydraulic and Electrical Machinery. — The turbine units are 
six in number, four driving the large generators and two furnishing 
power to the exciter dynamos. The former units are of a Four- 
neyron or outflow type, the water from the wheel runners dis- 
charging into a draft tube. They have vertical shafts, hydra ul- 
ically operated governors, and are direct-connected to. the 
generators. They have a rated capacity of 2,000 H.P. at full 
gate opening when working under 264-feet head. 

The exciter turbines, which are of the Girard type, develop 
100 H.P. at full gate opening when operating under the above- 
mentioned head. They also have vertical shafts, direct- connected 
to the dynamos, the speed regulation being under hand control. 
The supply pipes of each exciter turbine, which are 12 inches in 
diameter, are attached to the penstock of the units nearest them, 
the flow of water being controlled by a gate valve operated by 
hand power only. 

The main generators are alternators of the internal revolving- 
field type, producing three-phase current at 2,300 volts, and 60 
cycles when the field is rotating at 300 r.p.m. The exciter dynamos 
are 125-volt machines and revolve normally at 750 r.p.m. 

The switchboard is of the usual type, having a marble panel 
for each of the large units and one panel for the two exciter units. 
It also has separate high- and low-tension feeder panels. The 
potential of the current leaving the low- tension feeder panel, is 
stepped up to 23,000 volts by air-cooled transformers, from which 
the current passes to the high-tension feeder panel, thence out of 
the building through the lightning arresters located in a separate 
building near the power-house, and finally along the transmission 
line to the substation in Utica, twelve miles away. 

The Power-house. — The power-house, which is situated in a 
rocky gorge slightly more than 100 feet in width and varying from 
125 to 150 feet in depth, is a well-appointed building in all respects. 
It is 32 feet wide and 128 feet long inside, and around the skeleton 



214 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

steel framework are built walls of Gouverneur marble, while the 
interior is trimmed with white and brown enamel brick to the win- 
dow sills, and above this point with cream pressed brick to the roof. 
It is furnished with a io-ton travelling crane for convenience in 



Fig. 107. — Cross-section of Power-house. 

handling any part of the hydraulic or electrical machinery. A 
view of the interior of the power-house is shown. The turbines 
are all below the granolithic floor, in separate wheel pits. 

One important feature of the plant is there is no trouble from 



MC CALL FERRY PLANT 2 1 5 - 

anchor ice, due to two precautions which were taken when the 
dam was built. First, the pipe line enters the dam 40 feet below 
the surface of the water, and anchor ice does not sink to the level 
of the pipes. : Second, the crest of the spillway which carries sur- 
plus water around the ends of the dam is 2 feet lower than the 
spillway on the dam, and a strong current is thus established which 
carries the anchor ice around the end of the dam, and far away 
from the pipe-line intake, which is on the opposite side of the stream. 

At Utica there are two modern direct-connected steam stations, 
with a total capacity of 8,000 H.P., which can be started at once in 
case of interruption of the transmission lines from Trenton Falls. 
The last steam unit, which was installed last fall, is a 3,000 H.P. 
steam turbine, and generator of same capacity. 

Extensions. — The company proposes to add 8,000 H.P. to its 
Trenton Falls station, bringing its capacity up to 16,000 H.P., 
and also develop its water power at Prospect, about one mile above 
Trenton Falls dam. At Prospect a plant having a capacity of 
6,500 H.P. will be built, and at Enos on the Black River, nine miles 
from Prospect, the company will build a station having a capacity 
of 3,000 H.P.; thus the company will possess a grand total of 
25,500 H.P. in hydro-electric generators. 



THE HYDRO-ELECTRIC PLANT OF THE McCALL. 
FERRY POWER COMPANY. 

Abstracted from The Engineering Record oj September 21, 1907. 

There is now under construction at McCall Ferry, Pa., a hydro- 
electric plant having many unusual features in both design and 
methods of construction. It is on the Susquehanna River about 
25 miles from Chesapeake Bay. 

Hydraulic Conditions. — The Susquehanna River has a drain- 
age area of 27,400 square miles, the larger part lying in Penn- 
sylvania. Its watershed includes the steep slopes of the Allegheny 
Mountains, which cause sudden rises of rather frequent occurrence. 



2l6 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

The river occupies a deep valley, and for 125 miles above its mouth 
has an average slope of 3 J feet per mile, the fall atMcCall Ferry 
being 8 feet per mile. The conditions on which the design of the 
plant is based have been studied at Harrisburg since 1890 and at 
McCall Ferry since 1902. The records thus obtained show that 
with the adopted head of about 55 feet the flow of the river assisted 
by an adequate storage capacity can be depended upon for the con- 
tinuous development of 100,000 H.P. The storage will be se- 
cured by a lake 6 miles long and 4,000 feet wide, formed by the 
dam. The discharge necessary to develop the normal rating of 
the plant on a 12-hour load is 10,000 cubic feet per second, corre- 
sponding to an average run-off on the catchment area of 0.47 cubic 
foot per second per square mile, the drainage area above McCall 
Ferry being 26,766 square miles. The discharge as peak load will 
be 27,000 cubic feet per second. The flood flow considered in mak- 
ing the plans was about 671,000 cubic feet per second; the record 
of the highest flood, that of June, 1889, corresponding to an average 
run-off on the drainage area of about 25 cubic feet per second per 
square mile. The floods come with great rapidity, the flow 
in the river frequently jumping from 30,000 to 100,000 cubic 
feet per second or over. The necessity of providing carefully 
for these conditions is further emphasized by the large amount 
of ice earned toward the end of the winter, much of it in large, 
thick cakes. 

Dam. — The plant and dam are built at a point where the river 
is about 2,600 feet wide and divided into two channels by Fry 
Island. The east or Lancaster channel is about 900 feet wide, 
and the west or York channel about 1,200 feet, and the island about 
500 feet. The stream is only 400 feet wide a short distance above 
the dam, but the depth and swiftness of the current forbade con- 
struction there. The present site offers a ready means of handling 
the flow during construction by reason of the two channels. Above 
and below McCall Ferry the river is dotted with small islands and 
crossed by ledges, on one of which the dam rests. The water a 
short distance above and below it is very deep. Another such 



MCCALL FERRY PLANT 



217 



ledge crosses the river at Cully's Falls, and a channel had to be 
cut through it for the tail-race. The rock, though hard, is con- 
siderably eroded and fissured. 

On account of the floods, the dam has been constructed as a 
spillway throughout it's entire length of 2,350 feet. The dam 
extends only 600 feet across the Lancaster channel, the remainder 
of the channel being spanned by the power-house. Its crest is 
45 to 50 feet above the average summer water level. The section 




Engineering Record 

Fig. 108. — Section of Dam. 



has been calculated for a head of 17 J feet, above the crest corre- 
sponding to a flow of 304.7 cubic feet per second per linear foot of 
the dam, a quantity equal to the maximum recorded flow of the 
river. The section was calculated on the assumption that the 
weight of the masonry was 135 pounds per cubic foot, and the weight 
of the falling water over the dam and the pressure of the water on 
the apron were neglected. The base of the dam is uniformly 
65 feet wide, below a point 51 feet down from the crest. Where 
the dam crosses the island, the ledge rises to within 41 feet of the 
crest, necessitating a change in the section, which was made by 
retaining for the lower part of the apron the same curve as was 



2l8 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

used elsewhere, the only difference in the two sections being in the 
length of this lower curve of the apron. The front face is vertical. 

The dam is 1:3:5 Portland cement concrete with pudding 
stones up to 1 cubic yard in size. The sand is coarse and very 
clean, secured from a bank at Charlestown, Md. The stone is a very 
hard trap, weighing 193 pounds per cubic foot, used without screen- 
ing, and contains pieces running up to 7 inches in length. The 
pudding stones are of the same rock, which is obtained at 
a quarry operated by the company at Conowingo, Md. These 
stones, forming 20 per cent of the total yardage, are placed not 
closer together than 8 inches and 2 feet back from! the surface 
of the concrete. The amount of material in the dam is 174,000 
cubic yards. 

Power-house. — The power-house occupies the eastern part of 
the east or Lancaster channel, and stands at an angle of forty- two 
degrees with the face of^the main dam. In front elf it j is a forebay, 
where the racks and screens are located, and the entrances to the 
chutes for disposing of any ice which gets into the! enclosure. The 
conduits leading to the turbines start immediately back of the in- 
clined racks. They are built entirely of concrete, no steel being 
used either for reinforcing or for the intakes or draft tubes. The ten 
turbines are beneath the power-house floor, five on each side of the 
two exciters in the centre of the building. South of the power- 
house is the transformer-house, carried by arches spanning the 
draft-tube outlets in the tail-race. 

The front wall of the forebay is carried on 1 1 arches, the 
crowns of which are 6 feet below the crest of the dam, and 1 foot 
below the low-water level, so that they will always be submerged. 
Back of the arches and carried on inclined piers are the screens, 
and back of them are the gates closing the intakes to the turbines. 
The screens are built in panels 10 feet wide and 11 feet high, four 
tiers to a unit. They have frames of 10-inch channels, supporting 
the screen-bars, which are 7-16 X 4i inches, with 2-inch spaces 
between them. Instead of using gas-pipe separators, as is general- 
ly done, the bars are kept apart by plates | inch thick, which 



MCCALL FERRY PLANT 



219 




220 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

have notches cut in them of the thickness of the bars. The strips 
of metal between the notches are bent over the rods on which the 
bars are hung, thus holding the latter apart. The frames slide 
in cast-iron seats bolted to the noses of the inclined piers. This ar- 
rangement allows the screens to be withdrawn for repairs and clean- 
ing by merely catching them with a line from the crane, and pull- 
ing them out. Within the forebay are two chutes for disposing of 
any ice that may get by the exterior ice protection. One of these 
chutes 6 feet square is located between the two exciters at the centre 
of the power-house, and the other measuring 8 X 10 feet is at the 
east end of the forebay. 

The gates closing the intake conduits are 16 feet high and 6 
feet wide, and are raised and lowered by the large travelling crane 
in the screen and gate-room. An auxiliary gate, also lowered and 
raised by the crane, is cut into the main gate, and can be opened so 
as to equalize the pressure in the forebay and the intake conduits. 

The intake conduits for the main units start in three openings 
separated by piers each 6 feet wide and 16 feet high. Eight feet 
back from the gates these three passages merge into one which is 
15 feet wide, and for a short distance 13 feet high, expanding where 
the conduit forms the turbine chamber, to a height of 33 feet. There 
are two draft tubes, one leading from each wheel of the unit. 
These draft tubes join about 20 feet from the unit, but are here 
divided by a vertical wall, the discharge outlet into the tail-race of 
each unit being composed of two passages, each 13 feet wide and 
15 feet high. This arrangement of the draft tubes, since they are 
constructed of solid concrete, necessitated very complicated form- 
work, especially since it was necessary to have easily curving 
surfaces which would offer little or no resistance to the flow of 
water. The exciters are located in the centre of the power-house 
with five main units on each side of them. The intake conduits 
and draft tubes for them are 6 feet square in section. 

Each turbine is set in the concrete chamber without the usual 
steel or iron casing. Each chamber can be closed independently 
of all the others, and after being closed by the gates in front of the 



MCCALL FERRY PLANT 



221 



intake conduits and the stop-logs at the ends of the draft tubes, can be 
drained through outlets leading to pumps installed for that purpose. 




Below the power-house floor runs a chamber parallel to the 
length of the power-house in which will be installed the pumps for 



222 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

draining the wheel chambers and the turbine-driven oil pumps for 
supplying the thrust bearings with oil. 

The turbines are of the vertical shaft, inward and downward 
flow, Francis type. There are 10 main units each capable of 
developing 13,500 H.P. under a head of 53 feet with the gates open 
80 per cent at 94 r.p.m. Each turbine when run at its rated load 
will take about 2,700 cubic feet of water per second. Each tur- 
bine has two separate wheels mounted on the same shaft, the latter 
being of forged steel, 20 inches in diameter. The upper wheel 
discharges through a steel casing leading to the draft tube while 
the lower wheel is set immediately over the draft-tube pit, and dis- 
charges into it without the medium of a casing. The wheels are 
about 10 feet in diameter. 

The weight of all the moving parts of both generator and tur- 
bine is carried on a thrust bearing which is supplied with oil from 
pumps driven by small turbines. Separating the oil pumps in this 
manner from the main units allows the oil in the thrust bearing to 
be put under pressure before the unit is started. The thrust bear- 
ing, which carries a total weight of 335,000 pounds, is supported 
by a lens-shaped casting set into the concrete. The exciters 
have a capacity of 1,000 H.P. and are of the same general type as 
the main units. 

Ice Protection. — The large amount of ice which has to be dis- 
posed of and its long continuance each winter have necessitated 
special precautions for protecting the plant and turbines. It is 
aimed to keep the entire enclosed forebay free from ice, and to 
accomplish this an outer forebay is provided and separated from 
the main river by a series of submerged arches and timber cribs, 
which form racks holding in place floating booms. This ice pro- 
tection is 630 feet long, and stretches from the point where the 
main dam and the power-house join to a ramp 300 feet long built 
out from the shore. The concrete ice protection consists of 3 sub- 
merged arches each having a span of 68 feet with 8-feet piers be- 
tween them. The crowns of the arches are 2 feet below the esti- 
mated low- water elevation so that the arches are always submerged, 



MCCALL FERRY PLANT 223 

the ice and floating debris being thus stopped and floated toward 
the dam, where a special runway for this purpose has been con- 
structed between the main dam and the power-house. The top 
of this concrete structure rises to a height of 22 feet above the crest 
of the dam and 4 J feet above the high- water elevation. The top 
is 6 feet wide and the back face has a batter of 4 inches to the foot, 
the piers at rock foundation being 30 feet. long. The space be- 
tween the concrete structure and the ramp is occupied by four 
timber, rock-filled cribs, spaced 104 feet apart and supporting float- 
ing booms. These cribs are 24 feet wide and 16 feet long on top, 
the length increasing with the depth, being 64 feet at the foundation. 
The floating stop-logs between the cribs are made of three layers 
of six 10 X 1 2 -inch timbers each. They are bolted together with 
spaces between them so as to make the boom 7 feet 8 inches wide 
and 3 feet thick. The boom slides in recesses in the timber cribs, 
rising and falling with the stage of the water above the dam. 
The direction of the ice protection is parallel to the flow of the river 
so that the flow will assist in carrying the ice and debris toward 
the main dam and over the runway. 

In addition to this ice protection, a spillway has been provided 
between the power-house and the shore for disposing of any ice 
which forms in the forebay or finds its way into it. This spillway 
40 feet wide has the same elevation as the crest of the main dam. 
Separating it from the power-house and protecting the latter from 
the ice passing to the spillway is a wall 8 feet thick reaching above 
the high- water elevation. This spillway cuts off the power-house 
from the shore, and access between them is had by a bridge 5 feet 
wide, and by a tunnel 14 feet wide and 16 feet high running through 
it. The tunnel is laid with a standard-gauge track which extends 
55 feet inside the power-house, allowing the machinery to be handled 
directly from the cars by the power-house cranes. 

Tail-race. — The tail-race, 3,000 feet long, is nothing more than 
the former bed of the Lancaster channel, lying between the east 
bank of the river and the chain of islands south of Fry Island. 
This channel presents a very curious formation. The bed is of 



224 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

solid gneiss, with benches on either side submerged at the original 
condition of the river from 7 to 10 feet, and having between them 
a channel about 100 feet wide and from 80 to 90 feet deep, with 
vertical walls. This unusual depth continues until near the point 
where the tail-race flows into the main channel of the river. A 
ledge of rock is here encountered through which a channel 1,000 feet 
long and varying in width from 150 to 300 feet is blasted. In 
order to prevent the river from flooding the tail-race by flowing 
through the openings between the islands which separate the 
two channels, rock-filled timber cribs are thrown across these 
openings, and carried above the highest level which the water in 
the channel can reach. At the point where the rock ledge ob- 
structs the channel near the end of the tail-race a concrete weir is 
built, with its crest at the same elevation as the top of the draft- 
tube outlets, so as to preserve a water seal for the turbines. 

In order to prevent a large volume of the water which comes 
over the dam from finding its way at once into the tail-race, and thus 
raising the level of the latter, a deflecting dam 576 feet long starts 
at the junction of the main dam and the power-house, just opposite 
the beginning on the upstream side of the ice protection, and runs 
over to Piney Island, which lies south of Fry Island. This dam 
is built of solid concrete, using pudding stones and the propor- 
tions which were adopted for the main dam. Its crest is at the 
same level as the power-house floor, 14 feet below the crest of 
the main spillway. With this dam, and the cribwork between 
the islands below the plant, the water coming over the main dam, 
is confined entirely to the western or York channel, allowing the 
Lancaster channel to be used for the tail-race. The low- water level 
in the latter is about 15 feet below the water level in the spillway 
channel immediately below the dam. 

Construction. — Construction was first started across the Lan- 
caster channel, which carried the greater volume of water and in 
which the power-house is located. On account of the rapid rise 
of the river, and the large discharge during high water, the prob- 
lem of constructing the dam was a serious one. To have provided 



MCCALL FERRY PLANT 225 

against the maximum flood during construction would have in- 
volved great expense, while any less provision meant the occasional 
stoppage of the work, and the probable loss or damage of the con- 
struction equipment and the partially completed work. After a 
thorough study of all the conditions it was decided to construct a 
cofferdam sufficiently high to prevent being overtopped by a flood 
less than 60,000 cubic feet per second. Daily reports regarding 
the weather conditions on the watershed were received from the 
weather bureau at Harrisburg, and when a flood above 60,000 sec. 
feet was on the way preparations were made to meet it. Such a 
case occurred on March 15, 1907, when a flood of 320,000 cubic feet 
per second swept over the work. Warning had been received and 
everything movable in the path of the water was moved to a place 
of safety, and work carried on without interruption until within an 
hour of the arrival of the flood, when the remaining equipment 
was run to cover. The flood did no damage to the partially com- 
pleted dam and power-house, but carried off four standard-gauge 
tracks laid with 60 pound rail which were on the construction 
bridge below the dam. 

Cofferdam.- — The first step in the actual work of harnessing 
the river consisted in building the cofferdam, a rock-filled timber 
structure 1,000 feet long and about 300 feet up the river from the 
site of the dam. Soundings had been made across the channel 
at the places where the cribs were to rest, and, where these did not 
give a satisfactory description of the bottom, divers were sent down 
to get more accurate information. The bottoms of the cribs were 
then framed on shore to fit the rock foundation on which they were 
to rest, and, after having a few courses of timber built upon them, 
were launched, towed into position, and held there by cables 
anchored on shore. They were then built up in the usual manner, 
the timbers, which were 8 X 10 inches, being drift-bolted together 
with f-inch drift-bolts, 30 inches long. The materials were 
conveyed to the cribs by means of a cableway with a span of 
1,200 feet over the site of the cofferdam. In addition to this 
means of conveyance, a standard-gauge track was carried out and 



226 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

extended over each separate crib as soon as completed, and on it 
was run a travelling stiff-leg derrick. Rock was placed in the cribs 
to sink them as the timber work was carried up. The cribs were 
1 6 feet wide and varied in length, in multiples of 8 feet from 24 to 
40 feet, being built in bays 8 feet square. The deepest crib was 
about 30 feet below the original low- water level. 

The openings between the cribs were closed with stop-logs, 
and in front of them were placed two rows of 2 -inch timber sheeting 
breaking joints. The careful placing of this sheeting is largely 
responsible for the remarkable tightness of the cofferdam. The 
separate planks were driven to the bottom, rammed slightly, and 
on being drawn up showed by the bruising of the ends how they 
were to be cut to fit the rock bottom. After being shaped they 
were again put in place and rammed, and withdrawn a second time 
to determine whether further fitting was necessary. Against the 
sheeting was thrown the strippings from the excavations for the 
dam and power-house, a mixture of sand and loam, and on top 
of this a quantity of rip-rap. 

Foundation. — It was found that the rock bottom for the founda- 
tion of the power-house was of the same hard gneiss which had been 
examined, before the work commenced, on the banks of the river 
and the islands near the proposed site. Near the western end of 
the power-house, however, the rock became more dense, contained 
less mica, and finally merged into a very hard and dense trap, quite 
similar to that quarried at Conowingo and used in the concrete 
and for pudding stones. Examination showed it to be a dike which 
ran to Fry Island and then disappeared. Both the trap and gneiss 
were excellent foundations for the heavy structures, and test holes 
drilled the whole length of the work showed the same high quality 
of rock for a depth of 40 feet below the river-bed. The surface rock 
which was considerably eroded and fissured was removed, and at the 
shore end of the power-house about 50,000 cubic yards of the solid 
rock had to be taken out. The surface of the rock was then thor- 
oughly cleaned, and a layer of cement grout spread over it pre- 
liminary to placing the concrete. The amount placed at any one 



MCCALL FEERY PLANT 



227 




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o 

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228 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

time was governed by the strength of the forms, very close super- 
vision being given so as to guard against bulging. The bond be- 
tween successive sections is secured by embedding pudding stones 
in the surface of the work which is to be left to set. When the next 
course is added, the surface is first thoroughly swept with wire 
brushes, and then washed. Cement grout is spread over the sur- 
face, and the concrete work continued. 

Forms. — The forms for the turbine intakes, and chambers, and 
draft tubes were quite complicated, as everything is built of plain 
concrete. They were carefully designed and built by experienced 
form builders. In order to fashion the complicated curves on 
many of the forms, sheet iron and bass wood were used, the latter 
being bent into shape after being steamed. The forms were very 
heavily braced and tied across when possible by iron rods, as any 
bulging or displacement would result in altering the carefully de- 
signed water passages, and cause a loss of head by obstructing or 
changing the course of the flowing water. 

The forms for the dam consist of structural- steel bracing com- 
pletely spanning the section of the dam, and resting on two shoes, 
one on the upstream and one on the downstream side. They 
are placed 10 feet on centres, and the spaces between them are filled 
with framed wooden cradles bolted to the steel forms, and having 
the curves of the surface of the dam. The steel forms consist of a 
post with a total height of 57 feet supporting a rafter which runs 
over the apron, and rests on a shoe at a horizontal distance of 68 
feet 2J inches from the shoe under the post. Beneath the inclined 
rafter is carried a 12-inch 2oJ-pound channel having the exact 
curve of the apron. On the bottom of the channel is a 2 -inch tim- 
ber, bolted to it, and having a width of 1 foot 9J inches. Bolted to 
this strip are uprights 3 inches wide and 6 inches high on each side, 
having bolt holes through them by which the cradles are fastened 
between the steel frames. The cradles are each 8 feet 2§ inches 
long and 4 feet 2| inches wide, and each one is numbered according 
to an erecting diagram, for its proper place on the dam. On the 
channel sections the dam is being built in 40-feet piers, with 40-feet 



taylor's falls plant 229 

openings between them. For these piers five of the steel forms 
were used and braced together by diagonals, and by a large box 
beam connecting the forms above the crest of the dam. At the 
shore of Fry Island, where the section was changed, the steel forms 
could not be used because of the warped surface connecting the sec- 
tions. Wooden-braced forms were therefore put in place, and the 
value of the steel forms was demonstrated by the difficulty experi- 
enced at this point. The steel forms were used on the island section 
by merely unbolting the rafter at the center and allowing the two 
parts to overlap and pass each other, the lower part of the apron 
having the same curve on both sections, thus obviating the necessity 
of having two distinct sets of forms. The forms and cradles were 
placed, removed, and transported along the dam by the large cranes. 
It was not found necessary to provide any means for holding the 
forms down, as their weight alone was sufficient, but wires were 
passed through the dam, tying the vertical post and the rafter to- 
gether to prevent the latter from bulging. An additional advantage 
of the steel forms lies in- the saving in instrument work, it being 
necessary to set only the shoes with transit and level. 



THE TAYLOR'S FALLS-MINNEAPOLIS TRANSMISSION 

SYSTEM. 

Abstracted from The Electrical World of July 6, September 7, 

and October 5, 1907. 

There has recently been put into operation at Taylor's Falls, 
on the St. Croix River, 40 miles from Minneapolis, a water-power 
plant of a present capacity of 10,000 K.W. and an ultimate capacity 
of 20,000 K.W. It has been erected for the purpose of supplying 
power to the Minneapolis General Electric Company, which is the 
central station company of Minneapolis. This water-power plant 
and the transmission line and distribution system connected with 
it are among the notable recent engineering works of the country. 
Its capacity is sufficient to take care of all the present electric-light 



230 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

and power business in Minneapolis. The purpose of this article is 
to describe the water-power development of the falls. 

Hydraulic Development. — The St. Croix River is an excellent 
stream for water-power purposes, because it is fed by many lakes 
which act as storage reservoirs. The dam at Taylor's Falls is 50 
feet high and 740 feet long. A much shorter dam would have been 
sufficient to obstruct the flow of the river, but this length was given 
to provide a long spillway for flood waters. A map of the dam, 



Fig. 112. — Map of Works at Taylor's Falls. 

power plant, and river in the vicinity of the falls is shown in Fig. 
112. The original course of the stream is shown by the dotted 
lines, the river being naturally very narrow at this point. 

The power station is located on what was formerly a point of 
land, excavation having been made for the tail-race. By virtue 
of the tail-race excavation an effective head of 56 feet is obtained, 
although the dam is only 50 feet high. The location is almost 
an ideal one for the development of large power and storage 
capacity without excessive flooding of upstream land. The St. 
Croix River runs between high, narrow banks for the entire 11 



TAYLOR'S FALLS PLANT 23 1 

miles up-stream influenced by this dam. The only construction 
work which had to be done to prevent overflowing extensive land 
was the building of a concrete dike on the Minnesota side of the 
river, as shown in Fig. 112. Eleven miles above Taylor's Falls is 
Never' s Dam, owned by the same company and maintained for 
the purpose of storing water with which to supply the Taylor's 
Falls power plant in dry seasons. 

As seen by the map (Fig. 112), provision has been made for a 
log sluice on the Minnesota side of the river, entrance to which is 
through a bear-trap dam. A log boom extends across the river 
so as to divert logs to the sluice, and a swinging boom protecting the 
sluice is also placed above the bear-trap dam. A fishway is 
placed at one end of the power station, as indicated. 

The dam is simply a piece of solid concrete construction resting 
on bed-rock. The rock used in this construction was obtained 
on the spot. In many cases large chunks of trap rock were cleaned, 
dropped into place and surrounded by concrete, 6 inches on all 
sides. The concrete used in the dam was a mixture of one part 
cement, three of sand, and five of crushed stone from trap rock 
found on the place. Samples of each carload of cement were tested 
at the construction office at the falls. The first part of the dam was 
built with openings in the bottom through which the river was di- 
verted by a cofferdam when the remaining portion of the dam was 
being built. The forebay is protected by a drift boom located as 
shown in Fig. 112. Fig. 114 is a view of the forebay showing the 
ice and drift racks, which are easily accessible to workmen with 
rakes. A crane has been left in position for the purpose of lifting 
heavy driftwood out of the forebay if necessary. The dam proper 
extends clear through under the power-house, and the power-house 
building is erected on the face of the dam. Fig. 115 shows a cross- 
section of the dam at the power-house, the power-house foundation, 
showing the position of the intake pipe, turbines, and draft tubes. 
The intake pipe, 14 feet in diameter, has an elbow leading into the 
turbine casing. From the top of this elbow a 3-foot air vent pipe 
is led off. Over the middle of the turbine casing is an opening 



232 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

through which parts can be hoisted out for replacement or repairs. 
As will be seen from the cross-section drawing of the power-house 




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o 

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Pi 

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Ph 

Q 
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(Fig. 116), there is an I-beam on the ceiling of the wheel gallery 
which is located directly over this opening into the turbine casing. 



TAYLOR'S FALLS PLANT 233 

This I-beam carries an electric travelling hoist which can be run 
over any one of the turbines while repairs are going on, and with 
it parts can be carried to the end of the power-house. From the 
turbine casing two draft tubes 7 J feet in diameter drop to the tail- 
race. 

Power-House. — Before proceeding to a description of the gates, 
gate-operating machinery, and turbines, the general arrangement 
of the power station will be considered further. On the lower floor 




Fig. 114. — Forebay and Racks. 

is the generator-room, spanned by a 25-ton, 3-motor crane. On 
the second floor axe the transformer-rooms and switchboard. 
Each bank of three transformers is in a separate fireproof room 
and arranged to roll out onto the gallery under the main crane. 
On the same floor as the transformers, but separated from them, 
is the operating switchboard located so that the attendant can see 
from the gallery what is going on in the generator-room. The 
50,000-volt leads from the transformers go up through the floor to 
oil switches and then into bus compartments in a cell-room. From 
the cell-room the 50,000-volt conductors pass up to oil switches 
and from there to the protective apparatus and out to a steel 
tower, from which a span is made across the river to connect it to 
the pole line to Minneapolis. 

In the uppermost story of the power plant is the motor-operated 
gate-lifting mechanism. 

Turbines. — There are four turbine units each direct-connected 
to a 2,500-K.W. generator. Each of these turbine units has four 



234 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

runners 36 inches in diameter mounted on the same shaft. At 277 
r.p.m. the turbines are rated at 4,200 H. P. each with 55 feet head; 
at 48 feet head, 3,400 H.P.; at 45 feet head, 3,150 H. P. Therun- 




Scction ..tmroush fvUjN Unit 

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1/ 1 * \* 1* I ■ 'J 



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Elevation 

Fig. 115. — Elevation and Section of Power-house. 

ners are removable in the manner described in the general arrange- 
ment of the power-house. The penstock leading to each set of 
turbines is 14 feet in diameter and the two draft tubes 7 feet in 
diameter, the total effective head being 55 feet. 

The water-wheel speed is regulated with Lombard governors, 
these governors controlling the gates with oil pressure. The 



taylor's falls plant 



2 35 



oil-pressure tanks for the four governors are connected in mul- 
tiple. The wheel units can be started, stopped, and controlled 
from the switchboard by small motors mounted on the governor 
heads and so connected as to raise or lower the running speed of 
the governor. These governors were installed under a guaranty 
that an instantaneous variation of 20 per cent, in the load on the 
generator should not cause more than 2 per cent, speed variation, 
and that only for 4 seconds. In the case of the opening of a short- 
circuit on the generators the speed is guaranteed not to change 
over 12 per cent, and to return to normal within 7 seconds or less. 
The two turbines which drive the exciters have each a runner 




casting8 



Fig. 116. — Section of Power-house. 

18 inches in diameter. These turbines are rated at 200 H.P. at 
525 r.p.m. with 55 feet head. Besides being direct-connected 
to an exciter, one of these turbines can be connected through a fric- 
tion drive to a rotary fire pump for fire purposes. The friction 
drive is of the grooved-pulley type. 

Generators. — There are now installed four 2,500-K.W., three- 
phase, 60-cycle, 2, 300- volt generators. The power-house has room 




hi 



u 



a 



01 



d 



tailor's falls plant 



237 



for one more generator of this size at the end now occupied by the 
machine shop, and by extending the building three additional gen- 
erators can be installed, making a total capacity of eight 2,500-K.W. 
machines, or 20,000 K.W. The generators are guaranteed to take 
a load of 2,500 K.W. continuously and a load of 3,125 K.W. for two 
hours without exceeding the usual allowable temperature rise. 




Fig. 118. — Interior of Power-house, Taylor's Falls. 

Although their normal speed is 277 r.p.m., they are calculated to 
withstand 554 r.p.m. without excessive strain. If driven at con- 
stant speed the drop in voltage between no load and full load with 
constant field excitation is 6 per cent. The field-excitation current 
is 225 amperes at 125 volts. The efficiency at full load is 96 per 



238 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

cent., at three-fourths load 95 per cent., and at one-half load 93 per 
cent. The field-puncture test is 1,500 volts, and the armature test 
5,000 volts. 

The two water-wheel-driven exciters are 100 K.W., 125-volt 
machines, direct-connected to the water-wheels before described. 
These exciters, which have an overload capacity of 150 K.W. for 
two hours, are compound-wound with a series winding sufficient 
to maintain constant voltage from no load to full load; or, in 
other words, a flat characteristic. Their effective voltage can be 
varied by the rheostat between 90 and 130 volts. The efficiency 
at full load is 90 per cent., one-fourth load 80 per cent., and at 
50 per cent, overload 89 per cent. In Fig. 118 is seen a general 
interior view of the generator-room, showing the machines just 
described, one of the exciters, however, not having been installed 
when this view was taken. Room has been provided for the in- 
stallation of a 100-K.W. motor-driven exciter between the two 
other exciters when the power-house is extended. 

Transformer-rooms. — The transformer- rooms or -cells are among 
the most interesting features of the plant. The doors opening into 
these cells can be seen at the gallery on the right in Fig. 118, above 
each generator. There is one bank of transformers for each 
generator, and ordinarily a generator and its bank of transformers 
are considered as a unit, although provisions for separating them 
are made in the wiring scheme of the station, which will be de- 
scribed later. A view into one of the transformer cells is shown in 
Fig. 119. The transformer cells are of solid concrete with a fire- 
door opening onto the gallery in front. The fire-doors are held 
open by fusible links to allow the doors to slide shut in case of fire. 
The transformers are each of 900 K.W. The primary voltage is 
2,300 and the secondary voltage 50,000. They are oil' and water 
cooled, the water being piped from the forebay. The oil can be 
drained from the transformers by opening a valve which is accessible 
in the wheel gallery behind the transformer cells; thus, in case of 
fire in a transformer case, the oil can be drained off without enter- 
ing the cell, and the cell can be kept closed. As shown in Fig. 119, 



TAYLOR'S FALLS PLANT 239 

each transformer is mounted on a four-wheeled truck and there are 
tracks converging toward the door so that any one of the transform- 
ers can be run onto the gallery, where it can be picked up by the 
travelling crane. 

On the top floor of the building is an electrically heated oil- 
treating tank 4 feet in diameter X 8 feet long, in which enough 




Fig. 119. — Transformer Cell. 

oil can be treated for one transformer. It contains electric heating 
coils requiring a maximum of 45 K.W. When the oil is heated 
with these coils a motor-operated vacuum pump 8 inches in diam- 
eter X 6 inches stroke pumps out the steam that may be formed 
from any moisture in the oil. The power station is piped for 
transformer and switch oil. 

Switches and Wiring. — Each generator is connected directly 
to its bank of step-up transformers without the intervention of any 
oil switch, although there is a set of disconnecting switches in the 
leads of each generator before they come to the current and poten- 



240 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

tial transformers. In ordinary operation generators are connected 
in parallel by means of the oil switches on the 50,000-volt side of 
the transformer, thus putting them in parallel on the 50,000- 
volt bus-bars. The 50,000-volt bus-bars are therefore the usual 
operating bus-bars of the station. One set of 2, 300- volt bus-bars 
is operated, however, and branches from the leads of each gen- 
erator are taken to oil switches, by which each generator can be 
connected to the 2, 300- volt bus-bars. These 2, 300- volt bus-bars 
are ordinarily intended for use in supplying 2,300-volt current 
in the vicinity of the power plant. They can also be made a means 
of connecting a generator to a bank of transformers other than the 
one to which it is normally connected, as might be necessary in 
case of the break-down of a generator and a bank of transformers 
connected to another generator. The wiring scheme is designed 
for the completed power station; but not all of the circuits have 
as yet been installed. There is now a single set of 50,000-volt bus- 
bars. Provision is made for a double set of 50,000-volt bus-bars 
and an extra set of switches whereby each generator can be con- 
nected with either set of bus-bars. Static dischargers are con- 
nected between the generators and transformers, being located 
in the transformer cell-rooms. While provision is made for two 
outgoing 5o,oco-volt transmission lines, at present there is only 
one such line. There is an oil switch between the 50,000-volt bus- 
bars and the line. 

The 2,300-volt leads from each generator are carried in fibre 
conduit in the floor to recesses or cabinets in the wall at the right 
in Fig. 118. In these cabinets are the current and potential 
transformers from which low-tension wires are taken to the in- 
struments on the switchboard in the gallery. The generator leads 
then pass up to the primaries of the step-up transformers in the 
transformer-cell rooms above. The 50,000-volt secondary leads 
of these transformers are connected in delta in the transformer- 
room and then pass up through circular openings in the floor, filled 
with plate glass, to the bus-bar cells or compartments, to which a 
part of one floor of the power station is devoted. From the bus- 



TAYLOR'S FALLS PLANT 



241 



bar cells the wires lead up through similar circular floor openings 
to the 50,000-volt oil switches. 

The oil switches (which have a capacity of 1,500 amperes at 
50,000 volts) are considerably larger than are needed in this plant. 
They were originally built for another plant, but were sent to 
Taylor's Falls because of the urgency of delivery. They are sole- 
noid-operated and in reality consist of three enormous single-pole 
oil switches mechanically connected. At the right in Fig. 120 is 




Fig. 120. — 50,000 Volt, Oil Switches. 



seen the row of holes left for the high-tension conductors to the 
second set of 50,000-volt oil switches. The other openings in the 
floor are recesses left for oil piping. From the oil switches control- 
ling each bank of transformers the conductors pass down again to 
the 50,000-volt bus-bars. In the case of the oil switch connecting 
the 50,000-volt bus-bars to the transmission line the wires pass up 
from the oil switches to the series transformers and choke coils 

and thence out of the building. The general arrangement of 
16 



242 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

current transformer/ choke coil, and lightning arrester for one 
phase of the 50,000- volt line is shown in Fig. 121. Hook dis- 
connecting switches are provided on each side of all high-tension 
apparatus to provide for its isolation in case work is being done 
upon it. 

The operating switchboard is comparatively small and sim- 
ple, all of the operating switches in the main circuit being designed 
for remote control by low-tension circuits. These low-tension cir- 




ONLY ONE PHASE SHOWN" 



Fig. 121. — Connections of Transformer, Choke-coil and Lightning- 
arrester. 

cuits are obtained from the exciter. There are two negative ex- 
citer bus-bars, one of which is for local miscellaneous use in the 
power-house and the other for the field excitation. There is one 
common positive bus. Each exciter has simply a double-throw, 
single-pole switch for connecting it to either negative bus-bar, and 
an automatic circuit breaker. The totalizing panel for the board 
forms the centre of a semi-elliptical arrangement of switchboard 
panels. This totalizing panel contains an indicating wattmeter 
which, by means of a commutating switch, can have its connec- 
tion changed, so that, when the load is light, almost a full scale 



TAYLOR'S FALLS PLANT 243 

reading can be obtained, applying, of course, the proper constants 
to the reading to give the correct result. The other features of the 
board are those ordinarily found in such installations. 

J 

Gate-lifting Mechanism. — The main gates which admit the 
water from the forebay into the penstocks are raised and lowered 
by a motor-operated mechanism. A motor mounted on the ceiling 
drives a shaft that runs the length of the power-house. From this 
shaft is driven a counter- shaft at each gate. This countershaft has 
a worm-gear driving pinions engaging in racks on the gate. It is, 
of course, intended that only one gate shall be operated at a time. 
The mechanism for any gate can be brought into operation by 
throwing in a clutch. The controller for the motor is located 
on one wall of the building and is connected by a sprocket chain 
to a shaft which has two hand wheels at every gate, so that the 
motor can easily be stopped and started from any point. The 
height of the water in the forebay is continuously indicated and 
recorded by a Frieze water-level recorder. 

The regular operating force of this station, including both 
night and day shifts, consists of one chief engineer, two operators, 
and two oilers. 

The Line. 

The transmission line is 40.6 miles long and is designed to carry 
the total present capacity of the Taylor's Falls plant — namely, 
10,000 K.W. — with a line loss of 6 per cent, and a voltage drop 
of 10 per cent. It is built in almost an air line from the west side 
of the St. Croix River and Taylor's Falls to a substation at the city 
limits of Minneapolis. At the Minneapolis substation are step- 
down transformers for reducing from 47,500 to 13,800 volts. 
From this substation the transmission is at 13,800 volts to the vari- 
ous stations and substations of the Minneapolis General Electric 
Company. 

Pole Line. — A right of way 60 feet wide was purchased for the 
entire line. The right of way, however, is not fenced in, and farm- 
ers are allowed the use of the land just as before the purchase. The 



244 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

general direction of the line is northeast and southwest, so that it 
cuts diagonally across all fields. As the highways follow the sec- 
tion and half-section lines, the nearest highway zigzags across the 
line from one end to the other. As the country is dotted with small 
lakes, a number of these had to be crossed, and for such crossings 




Fig. 122. — Transmission Line. 



steel towers were employed. Fig. 122 is from a photograph of the 
typical straight-line construction. This shows also one of the 
telephone booths. Fig. 123 is a drawing showing the dimensions 
on a standard straight-line pole. The separation between wires 
is 6 feet. The conductors are No. 4-0 stranded, semi -hard-drawn 
copper. A four-pin telephone cross-arm is placed 7 feet below 
the transmission line. The poles are set from 100 feet to 120 feet 



TAYLOR'S FALLS PLANT 



245 



apart and vary in length according to the local conditions and con- 
tour of the country from 40 feet to 60 feet, the object of this being, 



= "2. 
T 



l_.l_U 



Fig. 123. — Standard Pole. 




Fig. 124. — Guyed Pole. 



LU 



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LU 




SgrfSWMff 



Fig. 125. — Transposition Pole. 



Fig. 126. 



of course, to avoid too sudden changes in the level of the conductors. 
The following pole dimensions were specified: 

For a length of 40 ft Tops 8 ins., butts 15 ins. 

For a length of 50 ft Tops 9 ins., butts 16 ins. 

For a length of 60 ft Tops 10 ins., butts 18 ins. 



246 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

The cross-arm braces are of ij-inches X 3-16-inch angle iron 
3 feet, 7J inches long. 

The main transmission cross-arms are 7 feet 4 inches long and 
5X7 inches in section. There are in all 12 telephone booths 
in 40.6 miles of line. There is a patrolman's cottage at the half- 
way point, the other patrolmen living at Taylor's Falls and Min- 
neapolis. For crossing lakes four sizes of steel towers are used — 
40, 45, 50, and 60 feet in height. Conductors are spaced 7 
feet apart on towers. There are 27 steel towers on the line on 
account of the large number of bogs and lakes to be crossed. 
The telephone wire is No. 10 semi-hard-drawn copper. Double 
cross-arms are used at all curves and pronounced changes in the 
profile. 

Fig. 126 is a drawing giving dimensions and foundation details 




Fig. 127. — Transposition of Conductors. 

for use when crossing a narrow stream. Fig. 127 shows the ar- 
rangement at the transposition of the transmission conductors. 
A transposition of one- third turn occurs every 3 \ miles. A double 
pole is used for this purpose. The telephone line is transposed 



TAYLOR'S FALLS PLANT 



247 



every tenth pole. Fig. 128 shows a pair of steel towers at the cross- 
ing of Leedholm Lake. 

Insulators and Pins. — The transmission-line insulator used is 
known as S. & W. No. 1, made by Locke. A cross-section of this 



# 



/FT 



/ 




Fig. 128. — Steel Towers. 



insulator is shown in Fig. 129. It consists of four parts held to- 
gether with neat cement. These insulators are shipped in crates, 
assembled, but without pins. The crates were provided with holes 



248 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

just the right size to take in the pin. The cementing in of pins 
was done before the insulators were uncrated, the crate thus serving 
the purpose of a template to hold the pins in position while the ce- 
ment dried. The insulator, as seen by the drawing, is 12^ inches 
high by 14 inches in diameter over all. The four parts were tested 
before assembling with a 60-cycle, 200-kilo-volt-ampere testing set. 




Fig. 129. — Insulator. 



The top piece withstood a test pressure of 60,000 volts; the second 
shell, 40,000 volts; the third shell, 50,000 volts; and the fourth 
inner shell or centre, 50,000 volts. The assembled insulator with- 
out cement was tested at 120,000 volts. 

The strain insulators, as shown in the guy wire in the illus- 
trations, consist of pieces of oak 2 J inches X 2 J inches and 30 inches 



TAYLOR'S FALLS PLANT 



249 



long, boiled in linseed oil. A tie wire of No. 2 solid copper is used 
for fastening the No. 4-0 stranded conductor on the 50,000-volt 
insulators. 

The insulator for the telephone line is a double petticoat 
2,300-volt porcelain insulator placed on a locust pin with a white- 
pine cross-arm. The cross-arms of the trans- 
mission line are of fir, unpainted. 

The pins for the transmission insulators 
are made from 2-inch extra-heavy steel pipe, 
with ends swedged down for cementing into 
the insulators. Fig. 130 shows the pin used 
on the cross-arms. This pin is held by a 
bolt passing at right angles through the cross- 
arm. The pins used on the pole tops have 
their lower ends flattened so as to bolt against 
the pole. Two pins out of every 100 are tested 
and must stand a lateral strain of 2,000 
pounds applied at a point 1 inch above the 
top, without yielding. 

Lightning Protection. — Few transmission 
lines have had so much attention given them 
as regards lightning protection. Minnesota 
thunder-storms are very severe, and it was felt 
that with a line of so much importance, upon 
which the electric-light and power service of 
a great city might be dependent there was every reason for 
obtaining the best in lightning protection. Of the lightning pro- 
tection appliances about to be described, many are of a partially 
experimental nature and have been put up with a view to deter- 
mining points about which there is at present considerable un- 
certainty. 

At each end of the line and in the middle, horn-type lightniiig 
arresters have been installed in accordance with Fig. 131. A 
rectangular cross-arm frame is built between four poles, and the 
necessary insulators mounted on these cross-arms. The horn 




Fig. 130. 



-Insulator 
Pin. 



250 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

spark-gap is adjustable from zero to 12 inches. Underneath 

the arrester is a platform, also mounted on transmission insulators. 

A water-column resistance can be inserted in the series with a 



Gap adjustable 
from to 12 in 




\ 






Fig. 131. — Horn Lightning Arresters. 




Fig. 132. — Choke Coils. 

ground wire from this arrester, this water-column resistance being 
described later. The choke coil used in connection with lightning 



TAYLOR'S FALLS PLANT 



251 



arresters is shown in Fig. 132. There is also a platform under 
these choke coils, so that the paper in the tell-tale spark-gaps, 
which are placed in shunt around choke coils, can be renewed. 
A tell-tale spark-gap which has been used in large numbers in 
getting records of static discharges on this line is shown in Fig. 133. 
Fig. 134 shows the framing used in connection with the adjustable 
spark-gaps, tell-tale spark-gaps, and fuses installed for obtaining 
records on discharges. 

The water-column resistance before referred to, which can be 
used in series with the ground wire of the horn arrester, is shown 
in Fig. 135. It consists of three 
galvanized- iron tanks or funnels, 
one for each leg of the circuit. 
These are mounted on transmis- 
sion insulators, and each is con- 
nected to the ground wire from a 
horn arrester. In the bottom of 
these tanks are five nozzles, one 
or all of which can be turned on 
according to the amount of water- 
column resistance it is desired to 
insert. 

Water from these nozzles falls 
into a grounded iron pan. This 

iron pan can be adjusted in height, as shown by the drawings, being 
suspended on pulley blocks. The water supply is piped to the 
arrester tanks by pipes discharging several feet above the tank. 
For purposes of obtaining records, every pin on every third pole 
of the transmission line has been grounded through a tell-tale spark- 
gap. Several experimental schemes of overhead grounds have 
also been installed on different portions of the line to determine the 
best construction. One form of overhead ground is to place a 
grounded wire at the centre of the transmission-wire triangle. 
Another plan has been to place grounded wires directly above the 
two lower wires of the triangle. Still another plan has been to place 




Fig. 133.— Tell-tale Spark- 
gap. 



252 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

a lightning rod on each pole with its point above the top wire of 
the transmission triangle. This lightning rod is fastened to the 
pole, and is bent out around the top transmission wire to keep it 




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a safe distance away. Another lightning-rod scheme installed is 
that of placing lightning rods on separate poles set alongside the 
transmission line, the rods extending about 25 feet above the level 



TAYLOR'S FALLS PLANT 



2 53 



of the top transmission wire. Tell-tale spark-gap boxes are in- 
serted in all ground wires. The line is looked after by four patrol- 
men. 

Distributing System. — The general plan is to decrease the E. 
M.F. from 47,500 to 13,800 volts at the city limits. From a step- 
down substation at the city limits 13, 800- volt, three-phase lines 
connect with the two old generating stations of the company, and 





Fig. 135. — Water Column Resistance. 



also supply energy to a number of small distributing substations, 
from which it is distributed at 2,300 volts, three-phase, to large in- 
dustries located in the immediate vicinity. It will be noted, 
therefore, that the distribution system possesses many features 
which have not heretofore been employed to any extent in large 
city systems. 

Substation at the City Limits. — At the city limits, at a main 
receiving substation, energy is received from the 40-mile 50,000- 
volt three-phase line. The building is thoroughly fireproof, and 



254 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

every precaution has been taken to prevent interruption of service, 
because all of the energy from Taylor's Falls must pass through 
it. This substation contains nine 900-K.W. transformers. 
Each transformer is mounted on a truck and can be run out 
onto a turn-table and from there over a track along the middle of 
the building to the door. The building is provided with concrete 
floors. Water for cooling the transformers is obtained from a 
deep well by means of a pump. There is also a cooling-pond 



Ground Wire 




Fig. 136. — Lightning Arrester Terminal Pole. 



adjoining the station into which water is discharged after pass- 
ing through the transformers. Water can either be circulated from 
the well or from the pond. The substation is provided with pipes 
for transformer, and switch oil, so that oil can be run into any trans- 
former case. There is also an oil- treating tank similar to that in 
the power station, as described in the article on the power station. 
The second floor of this substation is the switchboard and switch- 
room, shown in Fig. 137. The 47,500-volt wires are kept on one 
side of the station, and the 13.800-volt wires on the other side. 
Some of the high-tension wiring in the upper part of this floor of 



TAYLOR S FALLS PLANT 



255 



the building is shown in Fig. 138, where the 47, 500- volt wiring is 
seen on the right. The general scheme of the wiring of this main 
substation is shown in Fig. 139. The incoming 47, 500- volt trans- 
mission line, after passing the disconnecting switches, choke coils, 
and series transformers, is taken to a set of oil switches and thence 
through another set of disconnecting switches to the 47,500-volt 
bus-bars. The ultimate plan is to have tw T o sets of 47,500-volt bus- 
bars which can be connected with an oil junction switch. Every 




Fig. 137. — Switch-board Room over Transformer Room. 

other bank of transformers is connected to one set of bus-bars, and 
the remainder to the other set. The 13, 800- volt terminals of the 
transformers are connected to two sets of bus-bars in a similar 
manner. The city transmission lines are taken off from these lat- 
ter bus-bars and are led through oil switches and potential and 
series transformers to the transmission lines. 

The 13,000-volt Distribution. — There are three transmission 
lines leaving the main substation, all of which lines feed into 
the Main-Street station of the Minneapolis General Electric 



256 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 




Fig. 138. — Longitudinal Section of Main Substation Showing 

Wiring. 



taylor's falls plant 



257 



Company. This station has heretofore been the principal gen- 
erating plant. It contains both water-power and steam machin- 
ery, as will be briefly outlined later. This plant will act as a 
kind of distributing centre. At it the E.M.F. will be decreased 



50,000 Volt Incoming Lines 



Lightning Arresters 




! 1 J , 

A 4 A 6 AJ 



? ? 9 

m 



??? 



. "°; r °" 1r ° 1 



h-.-r'^s- 

A A & 
?f_P 

X., C+ JII o o — 

4 — j.— _|_I_ < o_ • 

Volt Busses I'M L 1 

. \-lj — ^4-r--« o o-T^f5> 

Pt- 4-tT — *r— '-f 00-.— A 

OOO 660 OOO Ti-Q't 

.. „ « === _ „ „ =£= „._ = = = Junction Sw h. 

P ? ? =f=ff P ? ? ffT p 9 f 

IT'S) fWoTol t^J loTfoiroi (,A , 

; ! AAA IliJ I ' i 6 A A 
1— L4 P 9 P 



III ! 1 A A A i 1 1, o r i 1 ' 1 d a 

■= =ut >"i4----?r r-tF^-?? j-M=-- 91 

ir^ ilT" iff - iS - 



• — o o 



Static 

Dischargers 



Vs-6"' 



Vo-6- 1 



■-5"oV 



200 I I I I Volt. TWsps I ! I ' I 



7J± 



III I ' 1 Volt Busses 1 1 ; 1 1 

fctt^^=----tL|^i^i4ircprSo4--J; jH i 

it-x -*-R-* s-Jn ^TVo-VlV^ Bub 

009 900009 Junc.Sw'h 

S-i-i- 1 
?»> 

1 

PPP 



■fri-s— 
ppf 

iTf 

M 



in 

ILL PLL 



?? p 1 1 



1 

?p? 

I rii rw li 1 



roiwryl 

1 ! 1 



1,1 
PPP 



LL,,lJJ n Static 
]~\~f T< — 1 Dischargers 
boo 00 A == = 
? f ILL' *ll 

I ~3"t !°!'°!p! 
"til *&« 

Trans, k-- J i £1 
PPf 



Dis.Swh. 



13,200 Volt Outgoing Linos 



[•jljilj, Light I J ) Cur. Trans. 
XT! A"' 8 * Wpot'l Trans. 
'■ -• A A o 

pff 

.-UJ-, 

1 Oil Sw h. 

' I A 

°°° Dis.Swh. 

r{=j=a- 



2300 Volt Local Line 



III 



i°'i°!i°; 3 

l°U°JI°J 60 



Fig. 139. — Wiring Diagram of Main Substation. 



to 2,300 volts for single-phase distribution for lighting pur- 
poses over the entire city outside of the downtown district. The 
downtown district is served with direct current from the Fifth- 
Street station, which is connected with the Main-Street station by 
two 1 3, 800- volt, three-phase lines, from which energy is obtained 
17 



258 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

for operating motor generators, step-down transformers, and rotary 
converters. The company's offices are in this substation; the 
building in this respect is very similar to the Edison buildings in 
a number of the large cities of the country. This station is well 
located to supply energy to the direct-current, three-wire network 
in the downtown district. The district is limited in area, extending 
only about half a mile in any one direction from the substation. 




Fig. 140. — Wiring in Top of Substation. 



When the area increases more direct-current substations will be 
established. 

The details of the overhead lines are of considerable interest, 
because of the use of an E.M.F. of 13,800 volts for general city 
distribution. On the standard pole top for the 13, 800- volt lines 
there are no lower voltage lines. The top cross-arm is designed 
for use with grounded guard wires, as will be explained later. 
The transmission wires are placed 2 feet apart. On a pole used 
for both 13,800- and 2,300-volt lines at a substation, the 2,300-volt 
lines are placed on the lower cross-arm. An elaborate pole fram- 
ing at a substation is shown in Fig. 141. This particular pole 
carries a telephone arm which is necessary on some of the lines. 



taylor's falls plant 



259 



Unusual provisions for lightning protection on the 13,800- 
volt lines had to be taken because of the severity of the lightning- 
storms and by reason of the fact that there are so many changes 
from overhead to underground lines. Two grounded guard 
wires are placed on the ends of the top cross-arm. At every third 
pole the guard wire is grounded to a coil in the bottom of the pole 



4 ^ 5 ?fiC3E 



-ij Ground 



T& 



s 



H 



6#0j£ 



§^ 



j 'a/ if 



1* 



5^0^" 



~K 



,- fl g /? 13200 VoIt~S 

n 1 aonn Vni* 4- 



m. 



tr 









XT 



.^ 



sjj'xe 



^v 7 



E 



B 13200 Volt 
-^ to Station 

-2, 13200 Voir 
— ' Line(Future) 1 



2300 Volt 
Power Arm 






X^ 



TF 



~^%rtW 



Tfr \ 2300 Volt 

from Sta. ^TF 



5^z632 



I 2300 Voiti 
Single Phase Arm 



t Telephone ArmT? 



- Curb. Line 



Side Elevation Ele.vation_Looking Toward Station 

Fig. 141. — Diagram of Pole Head at Substations. 

hole for new poles or to a pipe driven in the ground near the old 
poles. The guard wires are mounted on 2,300-volt insulators. 

All of the 13, 800- volt lines are laid underground except those 
in very sparsely settled portions of the city. One of the lines lead- 
ing from the main substation to a secondary substation passes 
underground at two railroad crossings before it reaches the under- 
ground district. lightning arresters are placed at all points of 
change from overhead to underground. To do this, miniature 
houses of asbestos lumber were built on the pole tops. Fig. 136 
shows the exterior appearance of these houses where the cable ter- 
minals are placed on the same poles. Here the cable is led up 



260 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 



into a terminal box and the choke coils are mounted between the 
poles. For the underground, 13,800-volt lines, cambric and paper 
insulated cables are used. Cambric is preferred to paper because 
it is less liable to become injured when handled roughly, and it is 
less susceptible to moisture. The cable has 6-3 2 -inch insulation 




< 00 

Fig. 142. — Section of Distributing Substations. 

over each conductor, and 6-32-inch over all conductors, with J-inch 
lead sheath. In making a joint on this cable, after the conductors 
have been spliced, each conductor is wrapped with cambric, and 
cambric tape sleeves or thimbles are used to hold the conductors 
apart when the joint is being finished. The joint, after being 
covered with lead, is impregnated with Minerallac or G. E. 67 com- 
pound. The insulators on the 13,800-volt overhead lines are of 
the Locke No. 3I type, of brown porcelain, and are placed on 
birch pins. 

Distributing Substations. — Between main substation No. 2 



TAYLOR'S FALLS PLANT 



261 



One Incoming Line 

One Transformer Bank 

One Outgoing Line 



Lightning 
Arrester 



r 

1 



Choke Coil 



13200 V. Bus 



Combined 



and the Main- Street station there are located along the three trans- 
mission lines various small substations. These substations, 
which form an interesting feature of the company's distribution, 
are intended for the purpose of 

4 

supplying large power consumers 
only, and each contains simply 
three step-down transformers for 
reducing the E.M.F. from 13,200 
to 2,300 volts, three-phase. There 
are no attendants at these sub- 
stations. They are located near 
large power users; it is the inten- 
tion to limit their output to 2,000 
K.W. Since more power than 
this will almost never be required 
at one plant, it is considered bet- 
ter to build another substation 
when the 2,000-K.W. limit is 
reached rather than to increase the 
size of the existing stations. Both 
the 13,800, and the 2, 300- volt 
lines are delta connected. The 
buildings are of galvanized cor- 
rugated iron. Since they are 
usually located in the railroad and 
manufacturing districts, their ap- 
pearance is not of great importance. 
Fig. 142 shows the interior arrangement of one of these distributing 
substations. Fig. 143 shows the general scheme of wiring a sub- 
station, the three legs of the circuit being indicated as one wire. 
The 1 3, 800- volt lines enter at one end of the building and pass down 
as shown in Fig. 143 through choke coils and a new type of com- 
pound switch and fuse rated at 300 amperes. The lightning ar- 
resters shown mounted at the right in Fig. 143 are of the new type 
of shunted-gap. 



Discharge Switch 



Transformer 



2300 V. Bus 




Oil Switch 



Choke Coil 



Fig. 143. — Diagram of Con- 
nections 



262 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

Main-Street Station. — The Main-Street station, which is located 
on the Mississippi River, in the heart of the city, was the principal 
generating station of the company's system before the circuits from 
Taylor's Falls were erected. This station is now operated partly 
by water power taken from the pondage above the St. Anthony 
Falls dam, partly by steam, and partly by electricity brought 
in over the tie lines from the main step-down substation of the 
Taylor's Falls system, mentioned in a previous article. The 
station is also arranged to act as an auxiliary to supplement the 
Taylor's Falls system at times of low water or accident. 

The general layout of the station consists of line shafts on 
one of which is mounted a i,ooo-K,W., 13,200-volt, three-phase 
machine which can be used to drive the shaft from energy received 
direct from the Taylor's Falls system or to be driven by the prime 
movers in the station, to deliver energy over the 13,800-volt tie 
lines to the step-down substations of the Taylor's Falls system or 
to the various substations scattered through the wholesale distrib- 
uting district. The line shafts are normally driven by the water- 
wheels, which are three in number, with a total capacity of 2,400 
H.P., assisted by the 1,000-K.W. machine operating as a motor. 
The relay capacity of the station is still further increased by a 
recently installed 1,500-K.W., 2, 300- volt steam turbo-genera- 
tor which is arranged to deliver energy directly to the 2, 300- volt 
bus or through the tie-line transformers to the tie lines or to the 
before-mentioned motor on the line shaft. Energy is supplied from 
this station for 2, 300- volt, two-phase, 60-cycle distribution, 500- volt, 
direct-current distribution and for both alternating-current and 
direct-current arc circuits from machines belted to the line shafts, 
from motor-generators and from constant-current transformers. 
In addition to its use as a motor or generator the 1,000-K.W. ma- 
chine on the line shaft is used as a synchronous condenser to control 
the power factor of the system. The station is arranged to allow 
the installation of additional machines of this type, and the general 
tendency is to simplify and consolidate the apparatus. 

Fijth- Street Station. — The Fifth- Street station is the main sub- 



KERN RIVER PLANT 263 

station of the Minneapolis system, located at the business centre of 
the city, where it is in the proper position to supply energy to the 
Edison low-tension system and to control the bulk of the business 
lighting. The station receives energy from the Main- Street station 
and the Taylor's Falls system; it contains steam auxiliary units 
and storage batteries. The steam auxiliary equipment consists 
of 600 K.W. rating of 230-volt, direct-current, direct-connected, 
engine-driven generators, 1,050 K.W. of 35-cycle rotary converters, 
650 K.W. rating (on one-hour discharge) of storage batteries; 
two 100-K.W., three-phase, 125- and 2 50- volt rotary converters, 
and 1,125 K.W. rating of 13,800-volt air-blast transformers and 
feeder regulators for the proper control of the potentials of distri- 
bution from this station. The high-tension and a large part of the 
low- tension apparatus of the station is operated from a remote con- 
trol switchboard. 

KERN RIVER NO. 1 POWER PLANT OF THE EDISON 
ELECTRIC COMPANY, LOS ANGELES. 

Abstracted from the Electrical World of August 10, 17, 24, and 

31, 1907. 

The Edison Electric Company of Los Angeles has com- 
pleted and placed in operation a power plant on Kern River, 
which, while not surpassing any previous records of high heads 
utilized or length of transmission, does embody in its construction 
many distinguishing features some of which are pronounced de- 
partures from previous practice. 

In capacity, the Kern River No. 1 power plant equals the 
rated capacity, 20,000 K.W., of the largest impulse-wheel plant 
previously in operation, and in overload capacity surpasses it. 
Its gravity conduit, constructed almost entirely of tunnels ex- 
cavated through the mountains, is the most permanent and cost- 
ly hydraulic waterway in the country. The pressure main, driven 
in the form of a tunnel, down the mountain slope, is probably the 
most unique feature of the installation and is a decided innova- 



264 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

lion in power-plant construction. The water-wheels embody new 
features in the design of buckets, nozzles, and governors. In the 
electrical details of the station is incorporated the most modern 
apparatus. The transmission line is at present operating at 60,- 
000 volts, which will later be raised to 75,000 volts. The length of 
transmission, 117 miles, is exceeded in only a few instances. More- 
over, the steel towers and insulators are of special design. 

The Kern River is the southernmost large tributary of the San 
Joaquin River, and has its head in the snow-covered slopes of Mt. 
Whitney and neighboring peaks in the Sierra Nevada Mountains. 

Water for the Kern River No. 1 plant is diverted at a point 
about one-half mile below Democrat Spring, in Kern County, 
and about 14 miles up the river from the mouth of the canyon. 
A hydraulic conduit, consisting almost entirely of a series of tun- 
nels, approximately nine miles in length, conveys the water through 
the mountains on the south side of the river to a forebay at a point 
about 900 feet above the river, and about two miles from the mouth 
of the canyon, where the plant of the Power Transit and Light 
Company, of Bakersfield, is located. 

From the forebay, the force main continues down to the power- 
house in an inclined tunnel. The power-house is located on the 
bank of the river directly opposite the intake of the Bakersfield 
plant, and at an elevation of about 20 feet above the ordinary high- 
water level of the stream at that point. The tail-race of the sta- 
tion is designed so as to deliver the water to the river immediately 
above the diversion point of the Bakersfield plant. 

The transmission circuits extend along the Kern Canyon and 
cross country to Los Angeles, 117 miles distant. 

Diverting Dam. — The dam which is built to divert the water 
from the Kern River into the hydraulic conduit is placed on bed- 
rock and is carried up to a point 1.25 feet above the flow line in the 
tunnel conduit, thus insuring a constant supply as long as the res- 
ervoir created by the dam is kept filled. In excavating for the 
dam, bedrock was found to exist at varying depths, the deep- 
est portion being at the south end at about 35 feet below the stream 



KERN RIVER PLANT 



265 



bed. A cofferdam was built to divert the river during the con- 
struction and while the fill overlaying the bedrock was being ex- 
cavated. Trenches were then cut in the bedrock and holes bored, 
in which steel bars were driven in two rows across the canyon. 
The first layers of concrete were placed on the bedrock and secured 
to it by means of the trenches and the steel bars. Cyclopean con- 
crete was the material of construction, the rock used being the 
granite found in the canyon. Many of the blocks were of large 




Fig. 144. — Map of Kern River Development. 



size, some weighing several tons each. About 1,500 cubic yards 
of material were placed in the foundation and 3,500 cubic yards 
in the dam proper. 

The dam is of the overflow type as shown in Fig. 145. 
Its length on the crest is 203.56 feet and its height above 
ordinary water-level in the river about 20 feet. At the base in 
the thickest part it is 52.81 feet wide. The crest has a small angle 
with the horizontal, and is 7 feet in width. The crest and lower 
face were designed so as to give a true hydraulic curve to the water 
overflowing, and to attain this end the upper 15 feet of the face 



266 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

was built with a batter of i to i so as to allow an air space under 
the water. The theory of the design is that air will enter this space 
under the water from the ends of the dam, and that enough will be 
carried down with the water to form an air cushion. With from 
2 feet to 3 feet of water flowing over the dam, a very smooth surface 
is presented. Below the forty-five-degree batter the downstream 




Fig. 145. — Cross-section of Dam. 

face has a radius of 100 feet. The upstream face has a batter of f 
inch to the foot. 

Headworks. — The head or diversion works of the gravity 
conduit consist of an enlarged or widened section of the intake tun- 
nel with controlling gates operated by means of hydraulic cylinders. 
In order to prevent contraction as the water enters and to afford 
sufficient screen area to admit the water, the tunnel is widened out 
at the entrance to 16 feet 6 inches. The screens or grizzlies are 
made of slanting bars and extend both in front and on the side of 
the controlling gates. The bars are \ inch X 3 inches and are 
spaced on edge, 3 inches between centres, by means of 2j-inch 
thimbles, the thimble rods being 4 feet apart. The screen is 20 
feet long on the slant and 8 feet high and is supported on 4-inch 
cast-iron pillars. 

Behind the screen and just above the gate is a 10-foot plat- 
form on to which can be raked any detritus caught by the screen. 



KERN RIVER PLANT 267 

The grade at the entrance of the diverting tunnel is increased above 
the normal grade so as to accelerate the water from its state of rest 
above the intake to normal velocity in the tunnel below. 

Another important feature of the headworks is the drainage 
or sluicing tunnel, 365 feet in length, that is driven through bed- 
rock below the intake at the south end of the dam, penetrating to 
the bottom of the reservoir above the diverting dam. A heavy 
grizzly, built of 70-pound T-rails, protects the entrance of this 
tunnel, and behind are two gates operated by hydraulic cylinders, 
by means of which the tunnel can be closed or opened as desired. 
The drainage tunnel was first used to divert the water from above 
the site of the dam during its construction to the river at a point 
some distance below the headworks. Its permanent purpose will 
be to sluice out, at such intervals as may be necessary, any silt 
accumulating in the reservoir above the dam. The gates of this 
drainage tunnel are constructed for operating under a pressure 
corresponding to from 35 feet to 45 feet, depending on the quantity 
of water flowing over the dam, the hydraulic cylinders for the gates 
being designed to move them under a head of 20 feet of water over 
the dam, should a flood of this magnitude ever occur. 

Each of the gate openings is 8 feet 10 J inches high and 3 feet 
8 inches wide, the side frames being of cast iron, and the sill a 
10-inch X iof-inch redwood timber. The gates are built of 5-16- 
inch steel plate and 6-inch 15-pound I-beams, the sides being formed 
of 12-inch I-beams. There are two cast-iron hydraulic cylinders 
installed in each gate. The set for the east gate is mounted on 
top of the concrete operating shaft, the west set being placed 
directly below, as there was not sufficient lateral space to place them 
both on the same level. The lower cylinders are placed 38 feet 
8 inches above the sill of the gate, and operate their gate by lifting 
rods 26 feet long. The upper cylinders operate their gate by means 
of 40-foot rods. These lifting rods are 4! inches in diameter, and 
are made of wrought iron encased in brass tubing to prevent rusting. 
The gates are guided at each side by four bronze rollers 3 inches in 
diameter. In order to equalize the pull of the two cylinders on each 



268 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

gate there are installed two racks 10 feet long and 6 inches wide 
into which mesh two 12-inch pinions mounted on the top of the 
gate. 

The gates for the intake tunnel are similarly constructed. The 
hydraulic cylinders, both for the intake gates and the sluice gates 
in the drainage tunnel, are operated by means of oil pressure 
supplied by gravity from a tank on the bank. The oil discharged 
from the cylinders is pumped up to this tank by a triplex pump, 
electrically driven, a sufficiently powerful hand pump being in- 
stalled for emergency use. 

Tunnels. — The hydraulic conduit of the Kern River plant is 
noteworthy by reason of its being the most permanent construction 
of its character in the country. The Edison Electric Company 
after its 14 years' practical experience with the construction and 
operation of hydro-electric power plants, has profited by the knowl- 
edge gained of the different forms of conduit used, such as timber 
flumes, earthen ditches, concrete-lined ditches, cement pipe and 
tunnels, and for its Kern River work determined that the most 
efficient, and, in the long run, economical construction would be 
a system of concrete-lined tunnels. The expense of driving the 
tunnels was a large item, but it was warranted in this instance be- 
cause of the large quantity of water handled and by reason of its 
permanency and the fact that it will be subject to practically no 
depreciation losses and but little expense for maintenance. An- 
other important feature of the tunnel construction is that there will 
be practically no evaporation loss from the conduit. As the evap- 
oration from the natural stream of the Kern River is estimated to be 
from 15 to 20 per cent when the water is low during the summer 
months, this factor will be an important one during periods of 
minimum flow. Another advantage of the closed conduit is that 
no leaves, sticks, or other debris can enter the water after it leaves 
the headworks. 

Between the intake and the forebay there are 19 tunnels form- 
ing approximately eight miles of gravity conduit. The number 
and length of these tunnels are given in the following table: 



KERN RIVER PLANT 



269 



Tunnels, Kern River No. i Power Plant. 



No. of Tunnel. 



hem 



3- 
4- 

5- 
6. 

7- 

8. 

9- 
10. 
11 . 
12. 

J 3- 

14- 

16. 

i7- 
18. 
19. 



th in 

595 
3.136 
4,049 

496 
1,522 
1,805 

874 
3,8i5 
2,049 
3,010 

2,587 
2,169 

2 ,335 
4,373 
3,767 
1,498 
1,898 
2,131 
794 



Feet, 
o 
6 
4 
3 
3 
1 
o 
8 

7 
8 
o 
9 
3 
7 
5 
4 
2 

5 
o 



Total 42,910. 5 

The tunnels are numbered from the intake down, Tunnel 
No. 1 being the intake tunnel, the entrance to which has already 
been described. 

The tunnels were .excavated in the rough to be 9 feet in width 
and 7 \ feet from the bottom to the spring line of the arch, and 
9 feet in height in the centre. Afterward they were lined with 
concrete 6 inches to 10 inches thick on each side and the floor paved 
with 3 inches of concrete, the net section thus obtained being 
8 feet in width by 7 feet in height. The entire surface of the side 
and floor was covered with a cement-mortar-plaster \ inch thick, 
composed of one part of cement to two parts of sand. At the cor- 
ners of the walls and floor a curve with a 3 -inch radius was formed 
in order to prevent wear at that point and also to smooth up the 
flow of water. 

The section of tunnel adopted is not the most favorable to 
give the highest velocity on a minimum slope, but is the most 
advantageous for the purpose, as by making a wider tunnel greater 
difficulties would have been encountered with the roof of the tunnel 
where it passed through loose or shattered formation. The grade 



270 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

of the tunnels is 7.92 feet per mile, it being intended that the water 
should be carried at a depth of 6J feet. The cross- sectional area 
of the stream is, therefore, 52 square feet, the wetted perimeter is 
21 feet, and the mean hydraulic radius 2.5. Assuming the coefficient 
of roughness to be 0.012 in Kutter's formula, the conduit has a 
discharge capacity of approximately 470 cubic feet per second. 
Experiments made on other tunnels of the company indicated that 
the coefficient would be about the value stated for this particular 
conduit. Observations made during the first few days after the 
conduit was placed in service showed that the coefficient is even 
less than 0.012. 

In places where the tunnels pass through seamy and shat- 
tered formation or "blocky" ground, they had to be arched over- 
head in order to support the roof, the concrete at the centre of the 
arch being from 12 inches to 18 inches thick. Less than 15 per 
cent, of the length of the tunnel required such overhead arching. 
Where this was necessary, it was placed by using a templet, with 
lagging overhead, the concrete being thrown back and tamped into 
place above the lagging. In excavating through this blocky 
ground, timbering was necessary, the standard bent formed of 6- 
inch X 8-inch sets, spaced 4 feet between centres and holding the 
rock back by 3-inch planks. In such sections the timbers were 
left in position and completely covered by concrete. 

The concrete at the sides was tamped into place behind boards 
supported by vertical forms. Wherever large cavities had been 
blasted out in driving the tunnels, they were filled with back-fill of 
riprap, the interstices of which were filled with sand and gravel. 
The same method was pursued above the concrete in the arches. 
Consequently there are no cavities existing between the bedrock 
and the concrete lining in the tunnels. 

In several places springs were encountered, and as the press- 
ure that would be created by stopping them up might be disas- 
strous to the tunnel lining, vents were installed through which the 
water can flow into the tunnel. These vents consist of sections 
of pipe from f inch to 3 inches in diameter and 6 inches to 8 



KERN RIVER PLANT 271 

inches long, set in the floor or wall and left open at both ends. 
The water, being under higher pressure than that flowing in the 
tunnel, continues to flow into the tunnel and thus relieves it of 
any strain. 

Portland cement was used throughout for the concrete, the 
mixture being in the proportion of i, 3, and 5. For the sand and 
aggregate, the granite excavated from the tunnels was used. The 
rock was crushed to i|-inch and 2-inch size, and for the sand 
was crushed and rolled so as to pass through a 60 screen. As no 
adequate water supplies were available along the route of the 
conduit, the water necessary for mixing the concrete had to be 
pumped up from the river. The men worked on two nine-hour 
shifts, illumination being furnished by a construction power plant. 
A total of 110,000 feet of lumber was used for forms on the concrete 
work. 

After the tunnels were completed, two two- wheeled hand carts 
with rubber-tired wheels were used for carrying cement and light 
tools for such finishing and repair work as was necessary. They 
were also brought into service in stringing the telephone line that 
is carried throughout the entire tunnel connecting the power-house 
with the diversion works at the dam. The two galvanized-iron 
wires of this telephone line are carried on inverted T-shaped brack- 
ets about 10 inches from the roof of the tunnel. The brackets are 
formed of J- inch pipe with porcelain insulators bolted on each end 
of the horizontal arm. The vertical pipe is secured in the holes 
of the rock or cement by wooden plugs. 

Timber Flumes. — The tunnel work was planned so as to avoid, 
wherever possible, flumes for spanning the side ravines encountered 
along the line. However, in order to maintain a good alignment 
and make the line as short as possible, a few exceptions had to be 
made to this rule. Some of these side ravines leading down to 
the main canyon and crossing the line of the conduit were on such 
a flat slope that should the timnel be constructed under the ravines, 
the necessary adits would have been very long. This not only 
would have increased the cost materially, but also would have 



272 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

added to the length of the line and the time required to do the 
work. At such points where there was no danger from falling rocks 
the ravines were spanned with flumes. There are six of these 
flumes, the number and length of which are given in the following 
table : 

Flumes, Kern River No. i Power Plant. 

No. of Flume. Length in Feet. 

1 1 ,029. 6 

2 129. 8 

3 (steel and concrete flume) 49-9 

4 73-5 

5 167.5 

6 70. 4 



Total 1,520 . 7 

All are constructed of timber except No. 3, which is built of 
reinforced concrete with a steel frame. 

Fig. 146 shows the method of constructing the timber flumes. 
They are placed on concrete foundations and are designed with 
a factor of safety sufficient to make their life from 30 to 40 years. 
The framework for supporting the flume box is of Oregon pine, 
being so designed and distributed that no part of the timber comes 
in contact with the earth or is exposed to the drip should the flume 
at any time spring a leak. In this way the life of the Oregon pine 
will be great. 

The flume box is built up of 3-inch X 12-inch planks of redwood 
grown in swamp lands west of the Coast Range in Northern Cali- 
fornia. The grade of this lumber is perfectly clear, and its quality 
is such that its life should not be less than 40 years. The edges 
of all planks were bevelled so as to give J- inch opening on the in- 
side of the joint, which is calked with ship chandler's oakum. 
The bottom seams were covered with hot asphaltum, and i-inch X 
6-inch redwood battens were nailed down over them. 

On the sides of these flumes a specially designed batten is 
used. This is of i-inch X 6-inch redwood, the upper half being 
cut away on a curve, permitting asphaltum to be poured be- 
tween the batten and the side of the flume. At the corners of 
the flumes a quarter-round strip is nailed. 



KERN RIVER PLANT 



273 



The design of the flume above described has been thorough- 
ly tested ; and even if it should remain dry for months in the hottest 
weather, its designers state that it may again be filled with water 
without having any perceptible leakage. 

In some cases, where crossing streams that are apt to carry 
considerable water in winter, span flumes are constructed. 

In connecting the wooden flume with the portal of a tunnel, 







Fig. 146. — Wooden Flume. 



use was made of a construction of a special nature, which offeis 

two points of contact between the wood and the concrete, and a 

well between the two, from which the water may be pumped out, 

and any leaks repaired should these ever occur between the wood 

and the concrete. 

St eel- Concrete Flume. — The flume between tunnels No. 6 and 

No. 7 across Laird Canyon is constructed of structural steel and 

concrete. The whole structure is carried on 15-inch steel I-beams 

set 8 feet 10 inches apart and supported by concrete piers. These 
18 



274 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

longitudinal girders carry 9-inch steel I-cross beams set 4 feet 
from centre to centre, and on them is erected a framework of 
structural steel for the sides and bottom of the flume. The 
layers of expanded metal (ij-inch and 3 -inch mesh) are used in 
connection with this framework and, filled with concrete, form 
the plates enclosing the frame. This concrete construction is also 
reinforced on the floor by twisted J-inch rods. The outside and 
inside of the flume were then plastered, making the thickness of 
the reinforced-concrete sides and bottom 4 inches. 

This type of flume or conduit has proved a decided success, 
and while it cost more than a wooden flume, it has the advantage 
of being as permanent as the tunnels themselves. 

Concrete Conduits. — In the lengths of tunnels and flumes enu- 
merated forming the gravity conduit for Kern River No. 1 power 
plant, no account is taken of the concrete conduits which connect 
some of the tunnels and which also connect the tunnels with the 
flumes. There were places along the line where the tunnel emerged 
at the foot of a steep incline in such a manner that the flume if 
constructed on the grade would be threatened by landslides or 
bowlders rolling down the side of the mountain. These places 
were spanned by means of concrete conduits, the interior of which 
has the same cross-section and slope as the tunnels themselves. 
The walls are made heavy and reinforced with steel and an arch 
overhead, the arch being covered with a cushion of earthen material 
to receive the impact of anything rolling or sliding down the hill and 
passing over the conduit. There are eight of these conduits, the 
following table giving the length of each : 

Concrete Conduits. Kern River No. i. 

No. of Conduit. Length in Feet. 

1 100 . 00 

2 69.4 

3 6 • 2 

4 * 42.2 

5 40 • o 

6 925 

7 3 J -6 

8 121. 6 



KERN RIVER PLANT 275 

Forebay. — A terminal equalizing reservoir of some size at the 
end of the gravity conduit and feeding the pressure main would have 
been desirable in connection with the Kern River No. i project. 
However, the side of Mt. Breckenridge, where the lower end of 
Tunnel No. 19 emerges above the power-house, is approximately 
on a forty-five-degree slope, making it impossible to excavate any 
large area for a terminal reservoir or forebay. It was necessary, 
however, to have a small basin for regulating the flow into the force 
main, and for this purpose a chamber 30 feet X 42 feet was ex- 
cavated to a depth of about 8 feet below the grade of the supply 
tunnel. Inside of this and over the mouth of the force main were 
erected controlling gates and screens through which the water 
passes into the force main. 

The walls of the forebay were made of concrete in the form 
of retaining walls where they were enclosed in the excavation, 
and on the lower side where they were unsupported they were 
made sufficiently heavy to withstand the pressure of the water 
on the inside of the forebay. As the formation where the structure is 
located is somewhat shattered, the concrete work was heavily rein- 
forced and the floor was paved with 3 feet of concrete. In the rear 
these walls were extended up to a considerable height to prevent ma- 
terial caving from the mountain above from dropping into the forebay. 

On one side is a spillway 9 feet above the floor of the forebay, 
and consisting of five 82 -inch openings over which the water flows 
into the waste flume when it is desired to divert part or all of the 
tunnel flow from the pressure main. The height of this spillway 
can be controlled by means of flash-boards which may be inserted 
and removed as required, according to the quantity of water carried 
through the tunnels. The extreme height of the spillway is 3 feet. 
A 24-inch gate valve is set at each end of the spillway for sluicing 
into the waste flume. 

The force main starts from the bottom of the forebay, thus 
making it possible to have the water enter it from opposite directions. 
This construction tends to prevent the formation of eddies or a 
whirlpool at the entrance. 



276 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

The controlling gates have an opening 6 feet 2 inches high and 
10 feet wide, and are built up of 4-inch X 12-inch timbers on two 
vertical 6-inch steel I-beams. They are raised by means of hand- 
operated gearing through four sets of gears working into two 
racks (7 inches wide and 3-inch pitch) mounted on the front of each 
gate. Behind the gates and inclined upward toward each other are 
two heavy trash-racks. These are formed of 3 J- inch X J- inch 
iron straps, spaced 3 -inch centres by thimbles of 2 J- inch wrought- 
iron pipe, the rows of thimbles being set 1 foot apart. Each screen 
is 11 feet 6 inches long and is set on an angle with its top supported 
by a 4-inch steel I-beam. These two beams are set 3 \ feet apart, 
the space between forming a walk. 

Waste Flume. — The forebay is constructed so that when the 
water is diverted from the force main it passes over the spillway 
automatically into the waste conduit extending down the mountain- 
side to the river. This conduit is of concrete at the upper end, 
where it is on comparatively flat grade, the section being 8 feet 
wide and 8 feet 6 inches high. The water is discharged into a 
redwood flume 20 feet wide, that carries it down the steep slope of 
the hill. As the slope is about forty-five degrees, no material except 
soft wood would stand the wear due to the high velocity. The 
spillway flume is 1,200 feet long and it discharges into the Kern 
River about 600 feet above the power station. 

The flume rests on 4-inch X 6-inch stringers bolted to 3-inch X 
3 -inch X f-inch anchor plates embedded in concrete footings. 
These footings are spaced 8 feet apart and are securely set, although 
they are not carried down to bedrock in all cases. The cross-beams 
of the flume are 4 inch X 6 inch timbers, 26 feet 6 inches long. 
The side posts are 4 inches square and are carried up 3 feet 3 inches, 
being secured at the bottom by angle plates. They are set 4 feet 
centre to centre, and are angle-braced by 4-inch X 4-inch pieces 
fastened at both ends by J-inch bolts. For lining the flume 2-inch 
X 12-inch redwood planks were used, the joints in the floor be- 
ing calked and covered with i-inch X 6-inch battens. Quarter 
rounds were nailed in the corners as in the other flumes. The 



KERN RIVER PLANT 277 

side lining, which is carried up 3 feet high, is battened and 
calked in the same manner as already described for the smaller 
flumes. 

Pressure Main. — The greatest innovation in the entire Kern 
River No. 1 plant is the pressure main, the construction of which 
has been along new lines and in decided contradistinction to the 
customary practice of laying a steel pipe on the surface of the moun- 
tain slope or merely burying it sufficiently to cover it for protection 
against freezing or expansion and contraction such as might be 
caused by a wide range of temperature changes. The pressure 
main constructed on Kern River consists of a tunnel approximately 
1,700 feet long driven through the mountain on an incline, and 
lined with steel varying in thickness from 3-16-inch to ij-inch. 
This tunnel begins at the bottom of the forebay, passes down at an 
angle of approximately forty-five degrees, and, turning into a horizon- 
tal section, emerges at the lower end on a level with the floor of the 
power station. There are three vertical curves in the tunnel. The 
upper one forms an angle of seven degrees 260 feet from the forebay 
floor. The second curve, 32.5 feet lower down, has an angle of five 
degrees and turns the pipe into a grade of 84.93 P er cen t. on which it 
is carried 994.24 feet to vertical curve No. 3. This latter curve has 
an angle of forty degrees and from its lower end the pipe continues 
along on a horizontal grade to the power-house, the total length 
of the main being 1,697 ^ eet - 

The pressure main is finished to give it an inside diameter of 
7 feet 6 inches. At the top a taper 20 feet long and 10 feet in diam- 
eter at the forebay entrance terminates in the regular 7 J-foot diam- 
eter of the completed tunnel tube. This diameter is maintained 
throughout the inclined tunnel, and on the horizontal beyond 
vertical curve No. 3 for a distance of 167.39 feet. At this point, 
1,454.44 feet from the forebay, the force main emerges from the 
solid rock and is carried to the portal, a distance of 243 feet through 
a detrital deposit lying between the mountain and the power-house 
site. Where the tunnel emerges from the solid rock a 20-foot taper 
was installed, reducing the diameter of the main from 7J feet to 



278 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

5 \ feet, at which diameter the pipe is carried to the branch piping 
at the power-house. 

The inclined part of the pressure main and the portion of the 
horizontal section that passes through solid rock were finished by 
installing a steel lining built up of plates 3-16-inch thick for the 
incline and f inch thick for the horizontal, riveted together to form 
a cylindrical pipe 7 J feet internal diameter. The tunnel itself was 
driven in approximately circular form and 9 feet in diameter. 
The steel pipe was centred in the tunnel, being installed in 10-foot 
sections, and the space between the outside of the steel lining and 
the bedrock was thoroughly filled with a mixture of concrete, con- 
sisting of three parts sand, three parts crushed rock, and one part 
Portland cement. The work of installing this lining was begun 
at the lower end in the horizontal section where the pipe is tapered 
down to the diameter of 5.25 feet. At this point the 20-foot taper 
already mentioned was placed, it consisting of if- inch steel plate 
riveted together with butt straps. The taper was placed back in 
the solid rock, and around it was constructed a heavy bulkhead of 
concrete which was anchored into the bedrock by means of steel 
rods driven into the sides. 

From this point the installation of the light steel lining with 
concrete back-fill, progressed from the bottom to the top of the 
tunnel, terminating at the reinforced concrete taper that connects 
with the floor and the forebay. The rock formation through 
which the force-main tunnel was driven is not of the best kind, 
being very much fractured and broken. It was necessary to 
timber the greater part of the shaft or incline when it was 
excavated, and these timbers had to be removed before the 
steel lining was installed. The timbers were removed ahead of 
the steelwork, the bedrock cleaned off, and the concrete tamped 
into place without difficulty. At a point about 120 feet below the 
top the men in charge removed some timbers without bracing the 
sets above. This precipitated a cave-in of the shaft, and several 
men lost their lives, one man being imprisoned for two weeks, after 
which time he was rescued in good condition. In retimbering the 



KERN RIVER PLANT 279 

caved portion, octagon steel sets of 7-inch, 15-pound I-beams were 
used. These sets were left in place when the concrete was put be- 
hind the steel lining. The lower end of the pressure main, from 
the taper reducing the diameter to 5 J feet in diameter, was made 
of if- inch steel plate, or sufficiently heavy to withstand the static 
pressure without any external support. No concrete was placed 
around this pipe, and the tunnel was merely left in its original con- 
dition with the timber sets to support the ground overhead. 

At a point 215 feet above the power-house a manhole was 
placed in the inclined tunnel for convenience in inspecting and 
for use in case any repair work is necessary. The regular 3-16- 
inch steel lining was replaced at this point by a section of 1 J- inch 
pipe 30 feet long. 

The steel pipe was shipped to Camp No. 1 at the power-house 
from San Francisco in 5 -foot lengths, five sections being nested 
together for shipment. The outside section was riveted complete 
on its two longitudinal seams, but the four inner sections were 
riveted on one seam only, so as to allow for the nesting. At the 
camp the pipe was riveted into 10-foot lengths and hoisted by means 
of an aerial tram to the forebay site at the upper end of the pressure 
tunnel. There the sections were secured to a dolly car, and lower- 
ed by means of a hoist to the point where they were riveted together. 
The car consisted of a truck at each end of the pipe section, the 
latter being hung from two timbers that passed through the pipe 
and rested on the axles of the trucks. 

All the piping in the pressure tunnel, which is constructed of 
steel plates of J-inch thickness and under, is made up with standard 
lap joints double riveted on the longitudinal seams and single 
riveted on round seams. All pipe on the work over \ inch in thick- 
ness is made up of butt-strapped joints throughout, with triple 
riveting on each side of the longitudinal seams and double riveting 
on each side of the round seams. 

After the steel lining was completed, an inspection of it revealed 
the fact that there were several places along the bottom of the pipe 
where voids had been formed in the concrete backing. These 



280 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

voids, which were revealed by tapping, were caused mainly by the 
difficulty experienced in tamping the concrete thoroughly around 
the sections of steel lining. The steel sections were 10 feet in 
length, and in a few places where large irregular rock excavation 
occurred at the bottom of a section with only a 9-inch space at the 
top for handling the tamping bars, some voids were naturally formed 
because of the insufficient tamping. 

Whenever a void occurred, a hole was drilled in the pipe and 
liquid cement was forced in until the hole was filled. The appara- 
tus designed on the spot to accomplish this work was an ingenious 
one. A section of 3 -inch steel tube 20 inches long was fitted at 
the bottom with a tap that would fit the hole drilled in the steel 
lining. Liquid cement was poured into the void by means of this 
pipe, which had a capacity of about an ordinary pail. When no 
more cement would run in, there was fitted in the pipe a screw with 
a plunger at the lower end and a crank on the outer end. By 
means of this device, the cement was forced into the void under 
pressure until it would hold no more. The pump was then re- 
moved and the hole in the lining stopped up by an ordinary flush 
pipe plug. There were 1 16 of these voids tapped and filled through 
the lining although only three of them were of large size. A num- 
ber of the voids required only a pint of the liquid cement, the quan- 
tity used varying up to the largest, for which 10 buckets of the slush 
was necessary. The slush used was a liquid mixture of Portland 
cement and sand. The work was carried on from a dolly car fitted 
with bevelled wheels and lowered down from the top by a steel ca- 
ble. About 15 days were necessary to complete this special work. 
After all the voids were filled the entire pipe was painted with 
asphaltum paint, the same dolly car being used for the purpose. 

Although the design of the pressure main has been criticised 
by some, it is believed that the construction will stand criticism 
and will prove to be permanent, and for that reason economical. 
The steel lining has a low factor of safety, being only heavy enough 
to keep its form and to resist the internal pressure, while all external 
pressure is taken up by the concrete back-filling, which, backed 



KERN RIVER PLANT 281 

up by the rock itself, also resists the internal pressures. Being 
entirely under ground and some distance from the surface, no 
trouble will be experienced by reason of expansion and contraction 
due to temperature changes. The anchorage is the mountain itself 
so that no disastrous effects could result to the pressure main from 
any water ram that might be caused by improper handling of the 
water-wheels or gate valves. 

Branch Piping. — At the lower end of the pressure main was 
constructed the header pipe, made of steel plates, varying in thick- 
ness from if inches at the inner end to j inch at the outer end, and 
consisting of the following specified lengths and diameters: 

Length. Diameter. 

33-5 ft 4i ft. pipe. 

23 . o ft 4J ft. pipe. 

21.0 ft. 3I ft. pipe. 

11 -5 & 3 ft - pipe- 

16 . 7 ft 2 J ft. pipe at the end. 

These diameters were graduated to maintain as nearly uni- 
form velocity as possible after withdrawing the water for the various 
branches to supply the water-wheel units in the power-house. In 
reducing the force main at the branch pipes to meet the diameters 
given, the following taper pipes were employed: 

1 taper 7. 5 ft. diameter to 5.25 ft. diameter, 20 ft. long. 

1 taper 5.25 ft. diameter to 4.75 ft. diameter, 10 ft. long. 

1 taper 4.75 ft. diameter to 4.25 ft. diameter, 10 ft. long. 

1 taper 4.25 ft. diameter to 3.75 ft. diameter, 10 ft. long. 

1 taper 3.75 ft. diameter to 3.00 ft. diameter, 10 ft. long. 

1 taper 3.00 ft. diameter to 2.33 ft. diameter, 10 ft. long. 

The branches from the force main were taken off by means 
of a Y on the header pipe and laid out in curved form entering the 
power-house at right angles to the rear wall. There is one branch 
28 inches inside diameter, 50 feet long, made of f-inch plate, for 
each of the eight water-wheels, and a 10-inch inside diameter branch 
pipe for each of the two exciters. 

At the end of the last section of the force main is a 28-inch gate 
valve which discharges into the river. 



282 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

In each of the branch pipes leading from the force main to the 
water-wheels are installed two 28-inch gate valves, one outside of 
the power-house and the other inside. The former is intended 
solely for the purpose of closing off the branch pipe in case of neces- 
sary repair to the gate or piping inside of the house. These outside 
gates are arranged only for hand drive, while those inside the power- 
house are equipped for operation either by hand or by electric motor 
as will be mentioned later. 

Power-House. — The pressure tunnel emerges from the side of 
M't. Breckenridge at an elevation above the sea of 1,061.95 feet. 
Directly in front of this point and slightly upstream there was a 
bowlder-covered wash protected by a bend of the river and bordered 
by a large mass of bedrock standing at the edge of the main channel 
of the river. This space was chosen as the power-house site. The 
intake of the Power, Transit and Light Company, of Bakersheld, is 
directly across the stream, and it is necessary to discharge the water 
from the wheels in such a direction and at such an elevation that 
it will flow by gravity into their intake. 

The Kern River is subject at times to very considerable floods, 
and the elevation of the header pipe and consequently of the water- 
wheels was made sufficiently high to permit of running the units 
even when the stream is at its maximum flood. 

The foundations were started on bedrock and cemented bowl- 
ers low enough to avoid any possibility of the power-house being 
undercut by floods, and the walls were constructed in such a manner 
that no important machinery rested on floors placed on back-fill. 
All spaces between these walls, except those which could not be 
utilized on account of their falling so low as to be subject to flood, 
were filled in with compact back-fill from other portions of the work. 

The available area was so crowded that it was necessary to 
make a deep excavation in the hillside to accommodate the inner 
or eastern end of the building. The debris from this cut and from 
the tail-races was wasted on the south side of the building as a 
dump upon which the header and branch piping from the pressure 
main were placed. On the north side of the station the spoil bank 



KERN RIVER PLANT 



283 



filled in a triangular area of the flat wash, raising its entire area 
above maximum high water and producing a bulkhead which will 
protect the power-house against any possible flood. 

The foundations proper are of monolithic concrete. The rock 
and part of the sand for the aggregate were secured by crushing 
granite bowlders excavated from the site, as well as a large amount 
of rock which was lying on the pressure- tunnel dump. Additional 
sand was secured for a time from various small bars in the river 




Fig. 147. — Plan of Power Station. 



adjacent to the power-house. These were, however, covered by 
high water early in the year, and after that time all necessary make- 
up sand was hauled from the mouth of the canyon, about two and 
one-half miles distant. 

The upper part of the machine foundations carries a small 
amount of reinforcement. The large block of masonry back of 
each water-wheel deflector is heavily reinforced and tied into the 
main foundation blocks. The crane-rail arches for the interior 
wall are reinforced concrete beams, with the exception of the long 
span above the switchboard, which contains an I-beam girder. 



284 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

By reason of the length of the building and the importance of the 
work, no account was taken in its construction of the additional 
strength resulting from the continuity of the beams, the bridging 
effect of the crane rail, nor its cushioning timbers, nor was any 
allowance made for the 12-inch curtain walls which fill in below 
this beam in places. The north wall, however, is a 12-inch curtain 
wall reinforced with heavy pilasters, and contains only sufficient 
reinforcement to render it reasonably secure against shock and 
vibration. The south wall of the building is of a cellular construc- 
tion for about two-thirds of its height, in order to provide wiring 
ducts for the 60,000- volt connections. This wall also contains only 
nominal reinforcement. Between this wall and the interior crane 
wall, a space 15 feet wide, a series of transverse partitions break 
up the area into transformer-, switch-, and switchboard-rooms. 
The transformer-rooms are open up to the crane beam to permit 
of wheeling the transformers out under the main crane. The crane- 
rail columns are not highly stressed and have no hooping whatever. 
A 50-ton electric travelling crane, with a 50-foot span, serves the 
entire machine-room. 

The switchboard space contains a deck 8 feet 6 inches above the 
floor level, upon which the control board is mounted. 

The roof of the building is of galvanized iron laid on wooden 
purlins, which are placed on steel roof trusses of 52-feet i-inch clear 
span. The internal length of the machine-room is 164 feet, and 
its clear width is 66 feet 6 inches. The generating units are located 
along the north side of the station, 78 feet from the centre of the 
pressure header. 

Other Hydraulic Features. — Dead water leaving the water- 
wheels flows down the floor of the wheel-race into the main tail-race. 
When the nozzles are deflected the water is diverted past the buckets 
onto a pair of heavy metal deflector plates. 

These deflector plates are 7 feet wide, and the lower one 
projects out into the tail-race 8 feet. 

The speed regulation of the water-wheels is effected by a gover- 
nor which deflects the jets of the two nozzles. The needles are ad- 



KERN RIVER PLANT 



285 



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286 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

justed by hand and are usually set to that maximum size of jet 
which will be sufficient to develop the maximum peak load ex- 
pected for that period of setting on the needles. In other- words, 
there is always a maximum amount of water leaving the nozzles. 
The governor adjusts the deflecting nozzles in such a way that only 
as much water is directed upon the buckets as is needed for the load 
for the time being; the balance discharges below the buckets into 
the tail-race. It is evident that at times when all load is thrown 
off the wheels, the governor will deflect the jets entirely. Each jet 
has a maximum diameter of 7$ inches, and leaves the nozzle tip 
at a velocity exceeding 225 feet per second. It was, therefore, 
necessary to provide means for receiving the tremendous force and 
for deflecting the jet into the tail-race. 

The arrangement designed consists of the pair of heavy de- 
flector plates onto which the jet is diverted, as noted above. The 
upper of these plates consists of a channel heavily ribbed and bolted 
to the concrete foundation. The channel at its upper end is slight- 
ly more inclined than the deflected jet. Thus the jet strikes the 
bottom of the channel under a small angle, and therefore tends to 
spread and fill the section of channel. The channel gradually 
widens, and consequently the jet is offered a larger resistance area. 
The lower part of the channel is curved, and at its end the jet dis- 
charges almost perpendicularly downward. The bottom plate is 
S-shaped, its upper end being flush with the bottom of the wheel- 
pit, the lower end practically level. The jet strikes the bottom 
plate almost in the turn of the " S " and under a small angle. Thus 
the jet is again forced to spread and follow the base of the bottom 
plate. In due consideration of the unavoidable wear and tear of 
these deflectors, they are lined with removable steel plates wherever 
the surfaces are exposed to the flow of the deflected jet, being held 
in position by lag screws. 

The wheel-races are lined with steel on both sides and fitted 
with steel plates just back of the nozzle tips to keep the splash 
water out of the shaft alley. 

The tail-race is 29 feet wide and extends the length of the power- 



KERN RIVER PLANT 287 

house. It is fitted with two 25-foot steel-plate weirs, the lower weir 
at the end of the tail-race being 4 feet below the level of the upper 
weir, which has its crest 13 feet 6 inches below the line of the nozzles. 

The water-wheel branch pipes enter the power-house at the 
south side and, after passing across under the transformer-room 
and before joining the nozzle bases, connect to 28-inch cast-steel 
gate valves. These valves are of a special design, and each is 
operated from the control switchboard by a 1.2-H.P., 120- volt motor. 
It requires 7 J minutes to open or close a valve by means of the 
motor. Each gate valve is equipped with a 4-inch by-pass. 

In the machine-room of the power-house is installed a Dibble 
reservoir gauge equipped with an indicating dial and a registering 
chart for measurements of the water in the forebay. 

Construction Plant. — A construction plant generating 300 K.W. 
at normal rating was installed for furnishing the energy used in 
driving tunnels, mixing concrete, transporting materials, etc. This 
construction plant was located at Frenchtown, or Camp 5, power 
being developed by means of a flume about 800 feet in length which 
supplies water under 40-foot head to two McCormick reaction tur- 
bines each operating one 150-K.W., 2, 300- volt generator. This 
plant furnished all the energy required while the work was in prog- 
ress, being frequently and for long periods operated at 50 per cent, 
overload, and was abandoned only after the completion of the main 
plant. From the construction plant, energy was transmitted at 
10,000 volts to all parts of the work over a temporary transmission 
line. 

Methods of Construction. — It can be said that the methods of 
construction employed were among the most modern known to 
engineering practice. For constructing the tunnels, air compres- 
sors were driven by motors using electric energy transmitted from 
the construction plant, as already stated, the air being piped into 
the various tunnels where it was used for operating pneumatic 
drills. Ventilating blowers for supplying fresh air at the face 
of the tunnels and for removing the fumes after a blast were operat- 
ed by electric motors. In the construction of the diverting dam, a 



288 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

complete system of cableways was installed, by means of which 
material was transported and placed in position in the dam. In 
the construction of the power-house, the handling of materials as 
well as the crushing of rock and mixing of concrete was carried on 
by means of the most modern equipment operated by electric 
motors. 

Water-Wheels. — The water-wheels selected for the Kern River 
No. i plant are of the impulse or tangential type. There are eight 
wheels installed, two for each of the four generators. The two 
wheels for each unit are overhung, one on each end of the generator 
shaft, the unit being of the two-bearing type. The water is pro- 
jected onto the buckets of the wheels through deflecting nozzles of 
the needle-valve type mounted at the end of the 28-inch branch 
pipes. By means of these deflecting nozzles and needle valves the 
discharge from the tip of each nozzle can be accurately regulated 
without altering the form of the jet to any appreciable extent. 

The wheels are designed to run at 250 r.p.m., and the two 
wheels on each unit are guaranteed to deliver a total of 10,750 
H.P. to the generator shaft. Regulation of the wheels is ob- 
tained by means of self-contained oil- actuated hydraulic gover- 
nors working under 125 pounds pressure. The governors act on 
the nozzles and deflect the stream off from or onto the buckets of 
the wheel as the load on the generator is decreased or increased. 
The governor for each unit is placed midway between the two 
nozzles and is connected to a common rock shaft which, in turn, 
actuates the two nozzles by means of rocker arms. These shafts 
are below the main floor and are accessible through a longitudinal 
shaft alley or tunnel 5 feet wide and having a clear head room of 
6 feet 9 inches. 

The nozzles are equipped with needles for adjusting the size 
of the stream by hand. For convenience in construction and to 
permit of balancing them for back-thrust, the needles are straight- 
backed, running through a guide sleeve of their full diameter into 
a balancing chamber supplied with water from the pressure side. 
The needle then reduces to a stem and passes through a second 



KERN RIVER PLANT 289 

stuffing box, beyond which the control links are attached. The 
needles are torpedo- shaped, being 8 feet long, 12 inches in diameter 
at their full diameter, and 8 J inches in diameter at the stem. The 
tip is about 25 inches long and is carried down to a blunt point on 
straight lines. The needle is operated by means of a hand wheel 
on the main floor, the wheel stand also supporting a pressure gauge 
connecting with the nozzle, and the two pipes connecting the two 
sides of the nozzle body with the balancing chamber of the needle. 
Each nozzle throws a jet 7! inches in diameter at full opening. 

The nozzle casting is bifurcated, the design being adopted to 
permit of bringing the needle stem out without offsetting the 
nozzle, as is done in other types of deflecting needle nozzles. The 
strain on the ball-joint bearings is equalized in this construction. 
The nozzle is a heavy steel casting, the Y portion weighing 1 5 tons. 
A counterbalancing plunger is located at the lower end of each 
operating lever below the nozzle. The needle stems and part of 
the tips are of steel. Some cast-iron tips have, however, been sup- 
plied, and it is expected that they will wear as satisfactorily as 
the steel ones. 

Each of the revolving elements of the wheels is 9 feet 8 inches in 
diameter, and consists of a cast-steel rim to which are bolted 18 
bronze buckets. These buckets are 27 J inches wide and are not 
radically different in form from modern buckets used elsewhere 
on the Pacific Coast, being in general of an ellipsoidal shape, 
with a straight front wall and a dividing wedge that dips down 
toward the front of the bucket. 

The housings of the wheels are of cast iron with graceful lines, 
and where the shaft enters are fitted with compound baffle plates or 
water guards to prevent water escaping from the housing. 

The combined moment of inertia of the revolving element in 
the two water-wheels and generator of each unit is W R 2 = 1,800,000 
pounds-feet, by means of which regulation at 100 per cent, load 
variation is obtained within less than 8 per cent, when the units 
are carrying 50 per cent, overload, and within less than 5 J per cent, 
variation of speed when running at normal load. The guarantee 

19 



290 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

requires that the water-wheel proper shall develop an efficiency at 
rated load of 82 J per cent., which guarantee is to be substantiated 
by tests conducted by the company. 

Governors. — When the governor arrangement for the water- 
wheels was designed, the leading idea was to have each turbine with 
its respective governor form an independent unit. Although the 
available operating water pressure of 370 pounds from the force 
main is ample to operate governors, it was preferred to substitute 
oil pressure. This precaution is fully justified, as long years of 
experience in operating hydraulic governors has proven that the 
safety is rather questionable, and the wear and tear of the parts 
of regulating valves causes a constant expense for repairing and re- 
placing parts, which necessitates shutting down the respective units. 
It was also deemed preferable not to feed the governors with oil 
pressure from a central system, but to make each governor abso- 
lutely self-contained. The oil pressure used is 125 pounds per 
square inch. 

Special attention was paid to the safe operation of the units, 
eliminating from the beginning any tendency to run away. For 
this purpose, the arrangement of the generator, as well as the 
exciter governor, was made in such a manner that the jets will 
be automatically deflected from the buckets whenever the oil 
pressure in the governor should fail. 

The weight of the two deflecting nozzles for each unit is partly 
carried by a hydraulic balancing piston placed midway between 
the nozzles, which receives water pressure directly from the force 
main. The governor arm connects by means of a link to a com- 
mon rock shaft, which in turn actuates the two nozzles by means 
of rocker arms. The design of the connection is such that as soon 
as the oil pressure in the governor fails, the nozzle will lower on 
account of the unbalanced weight, and thus deflect the jet from the 
buckets. The same result is accomplished with the deflecting 
hood of the exciter wheels, which is connected to a hydraulic water 
piston, tending always to insert the hood and thus deflect the jet. 

Each governor is driven by a Morse silent-running chain from 






KERN RIVER PLANT 29 1 

its wheel shaft. The connections between the operating pistons 
and the deflecting nozzles or hoods consist of levers, pins, links, and 
shafts. The use of gears or racks has been avoided, thereby pre- 
venting jars which would result in lost motion and wear and tear. 

Attention may be also called to the fact that all constituent parts, 
as well as all accessories, are attached or combined with one main 
casing, the advantage being that each governor can be assembled 
and thoroughly tested in the factor}', and shipped completely as- 
sembled to its final destination. The main casing contains the 
main operating cylinder with piston and mechanical hand-regulating 
device. The oil pump is attached to the casing and immersed in 
the oil reservoir. It is of the rotary type, having no valves, which 
are often the cause of failure of oil pressure. The main pump shaft 
also carries the bevel gear which drives the fly-balls operating the 
pilot valve over the regulating lever. The pilot valve is self-con- 
tained between opposing pressures, and any reaction upon the fly- 
balls is eliminated. It is evident that this is a principal condition 
for exact regulation. The pilot valve distributes the oil pressure 
in the regulating cylinder. The motion of the regulating piston 
is reversedly transmitted to the regulating valve by means of a 
combined compensation. The leverage of this compensation is 
adjustable, so that the governor may be set for any load-speed 
characteristic, from 16 per cent, to absolutely constant speed. 

The governors are equipped with four regulating devices 
which can be used at any time: i. Mechanical hand regulation 
(without oil pressure). 2. Automatic regulation with fly-balls. 

3. Hand regulation with oil pressure (fly-balls disconnected by 
a clutch coupling inserted between pump shaft and fly-ball shaft). 

4. Hand regulation with oil pressure and electric motor operated 
from the switchboard. (Synchronizing attachment.) 

The exciter governors are of similar design, except that they 
are not provided for electric hand regulation. 

There are two exciter units, each being of the two-bearing 
type, with an impulse water-wheel on one end and a heavy fly- 
wheel designed to give the unit close regulation on the other end 



292 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

of the shaft. The exciter wheels are operated from stationary 
needle nozzles, the needles being of the same straight form used on 
the main wheels. Regulation is obtained by oil governors which 
operate stream deflectors that are pulled up into the stream from 
below as the load on the unit decreases, thus deflecting a part or 
all of the stream into the tail-race. The exciter wheels are of a con- 
struction similar to the large wheels, having 20 bronze buckets 
9! inches wide bolted to the rim of the runner. 

Generators. — The main generators have a rated output of 5,000 
K.W. each. The stationary armature is bar- wound for 2,300 
volts, three-phase, 50 cycles. Each main unit is provided with two 
16-inch X 48-inch babbitted bearings, each fitted with six oil rings. 
In the pedestals the oil is cooled by means of water coils. Each 
bearing also has in its lower portion a number of small openings 
which are connected to a triplex motor-driven pump, capable of 
circulating the lubricating oil under a pressure of 1,000 pounds to 
the square inch. 

The generator shaft is flared out at each end to form a flange 
to which is bolted the wheel disk. The shaft is also enlarged at 
the centre to carry the cast-steel pole rim and spider. This latter 
is a single casting weighing twenty-six tons. The pole pieces are 
wedged to the exterior of this rim. 

The exciter units are standard 225-K.W. direct- current ma- 
chines, generating at 125 volts, flat compounded, running at 430 
r.p.m., and have ordinary self-adjusting bearings. Sufficient 
space has been left between the two exciters to permit the installa- 
tion of a large induction motor at some future time if it should be 
found necessary. This motor would be designed for good speed 
regulation and arranged so that it could be connected by means of 
a pair of clutches to either of the exciters. 

Output 0} the Plant. — The normal rated output of the Kern 
River No. 1 power plant is 20,000 K.W. The machinery is tested 
to operate under 50 per cent, overload for peak load service, thus 
making the maximum capacity of the installation 30,000 K.W. 

Transformers. — The station contains thirteen, 50-cycle, 1,667- 



KERN RIVER PLANT 293 

K.W., oil-filled, shell-type, oil-circulated, one-phase transformers in 
boiler-iron cases. These transformers are grouped in four banks of 
three each, with one spare, to receive power at 2,300 volts delta from 
the generators, and to supply it to the line at 75,000 volts Y. 
Taps are also provided for the intermediate voltages of 56,250 and 

37,5°°- 

These transformers, instead of having internal water-cooling 

coils, are so built that when the oil is supplied to them under a slight 
pressure it will automatically distribute itself throughout their 
windings and return itself by gravity to the waste pipe. The pip- 
ing and connections for this circulation, which are placed in the 
basement of the power-house, consist of a 4-inch supply line, a 
6-inch return line, and a 4-inch waste. These principal pipes are 
placed in a tunnel 7 feet 9 inches wide and n feet high, extending 
the length of the building. 

The oil coming from the transformers enters a receiving drum 
from which it is drawn by two 5 -inch centrifugal pumps, driven 
by 15-H.P., variable- speed, shunt-wound, direct-current motors. 
Either pump can supply oil to the entire equipment of transformers 
in an emergency. These pumps force the oil through a set of boiler- 
tube coolers set over the tail-race, consisting of a series of 2 -inch 
pipe, 10 feet long, made up in four sections containing 1,008 tubes, 
and having a total area of 4,500 square feet. From these cooling- 
coils the oil returns to the pressure line, from which it is supplied 
to the transformers. 

This system has been carefully laid out with strainers, by-passes, 
and other auxiliaries so that the entrance of any foreign substances 
into the oil will not cause trouble. As the system is under pressure 
from the time the oil enters the pump, any leakage will be outward 
and there will be no possibility of water leaking into the oil, as is 
the case where the water coils under pressure are placed in oil- 
filled transformers. The oil is specially refined. Another ad- 
vantage of a system of this kind is that the cost of installation is 
somewhat less than for a similar installation using water-cooling. 

Water for the cooling-sections is by-passed from one or both 



294 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

of the exciter tail-races into a flume built across the top of the 
coolers. 

Electric Details oj Station. — The generator leads pass through 
ducts, under the station floor, to the generator switches, and from 
thence to the low-tension side of the transformer banks. The 
station is not equipped with a complete 2, 300-volt bus-bar system. 
There are, however, motor-operated, oil tie switches placed between 



»*K 




Fig. 149. — Cooling-coil for Circulating Transformer Oil. 



adjacent machines and equipped with double- throw switches in 
such a manner that, in case of necessity, any generator can be 
transferred by means of this transfer line to any single transformer 
bank, or run in multiple with some other generator on a single 
transformer bank, or, if desired, the entire station can be tied 
together by means of this transfer bus and operated as a single unit. 
The transformer banks connect on their high-tension side 
through knife-blade switches to a single bus-bar, which is sectioned 



KERN RIVER PLANT 



2 95 



in the middle. The two outgoing transmission circuits are tapped 
off this bus-bar between adjacent transformer banks through motor- 
operated oil switches. These switches are remote-control, non- 
automatic. By use of them and the section oil switch, all high- 
tension power switching can be handled without the use of air- 
break switches. At the same time the investment for high-grade 
switching is reduced to a minimum. The 2,300-volt oil switches 




Fig. 150. — Switchboard. 



are installed in cells with concrete barrier walls and tops. The 
disconnecting switches for them are also separated by barrier wails 
where possible. The 7 5, 00c- volt oil switches are not only installed 
in concrete cells in accordance with standard practice, but each of 
them is enclosed in a separate concrete room containing no addi- 
tional apparatus except lightning arresters. 

The control switchboard is mounted on a gallery overlooking 
the machine-room. It is built of black slate and is a combination 



296 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

bench and panel board, consisting of nine divisions. The first 
panel on the left controls the station auxiliaries, the feeder for 
which is taken off the two centre sections of the 2, 300- volt bus 
through solenoid-operated oil switches and then through two sole- 
noid-operated oil switches to the panel. 

The second and third panels are equipped for handling the 
exciter circuits, and each is provided with an ammeter, a voltmeter, 
and two single-pole, double-throw knife switches for connecting 
the exciter to either of the two exciter buses. The panel also has 
two double-pole, double-throw switches for connecting the exciter 
bus to the station lighting circuit and to the operating buses which 




Fig. 151. — Disconnecting Switch and Choke-coil. 

control the oil-switch motors, the lamps on the control board, and 
other auxiliaries. 

Panel No. 4 is blank, while Nos. 5, 6, 8, and 9 are generator 
panels. Each of the latter is equipped with three Thomson am- 
meters, a field astatic ammeter, a curve-drawing ammeter, a curve- 
drawing voltmeter, and a curve-drawing wattmeter. 

The seventh panel is the auxiliary feeder, bus-sectionalizing 
and station panel. It contains a synchronism indicator and two 
voltmeters on the synchronizing bus, an ammeter on the ground 
circuit, and an ammeter on the auxiliary feeders. 

The bench of the switchboard has controlling switches with 
red and green signal lamps for each of the four generators, and 
there are also provided control switches for each of the two 2,300- 
volt feeder switches, for the switches on the 2,300-volt bus sections, 
and for the 75,000-volt outgoing line switches. The base of each 



KERN RIVER PLANT 297 

generator bench panel has one governor control switch and a 
double-pole, double-throw control switch for operating the two 
28-inch valves on each water-wheel unit. 

On the six-panel rear switchboard are mounted five polyphase 
watt-hour meters, break switches, and disconnecting switches on 
the field circuits. A curve-drawing, frequency-registering meter, 
driven by a J-H.P. motor, is also installed. 

The high-tension wiring is run in 4-foot square ducts through- 
out, no open wiring being permitted except connections from trans- 
formers to the wall through their disconnecting switches, and from 
the lightning arrester disconnecting switches to the lightning- 
arrester banks. 

The lightning arresters are of multiplex type, consisting of 
alternate carbon spark-gaps and resistances. The circuits are 
equipped with choke coils, consisting of 20 turns of hard-drawn 
copper. The lightning arresters are mounted in concrete-wall 
cells, and are so completely isolated from each other by the inter- 
vening main-line ducts that an arc starting on any single arrester 
could not by any possibility be transferred to a second bank. 

The leads, after passing the choke coils and taps for the light- 
ning arresters, pass out of the south wall of the building through 
rectangular openings located immediately below the eaves. To 
prevent the drip from the long run of roof from falling on the wires, 
a gutter extends for a few feet across the roof above each entrance. 
From the eaves of the building, the leads converge onto the first 
tower of the transmission line. 

Transmission Line — Route. — From the power-house the trans- 
mission line runs, as near as may be in a straight line to the mouth 
of the Kern River Canyon, 2 J miles distant, where it sweeps off 
to the left across the Cottonwood Hills, and then takes a due south 
course across the edge of the Bakersfield plains. The line then 
enters the mountainous section through Tejon Canyon, follows 
across the end of Castaic Lake, and crosses the Coast Range di- 
vide immediately above German Station. 

This is the steepest portion of the transmission line, as the 



298 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

drop from the top of the hill to the road below is over 1,000 feet in 
3,500 feet. From here south the transmission line follows the waters 
of Piru Creek and its tributaries, the character of the country 
changing gradually from low, rounded hills with grassy slopes to 




Scate 

o /o zo so 

I I I I ' ■ ' 



Fig. 152. — Map of Transmission Line. 

deep, narrow gorges walled w T ith precipitous shale cliffs capped with 
sandstone ledges. 

A section here of about 5 miles involved very difficult work. 
Heavy angles, both vertical and horizontal, were necessary in a 
district where no permanent wagon road could be maintained 



KERN RIVER PLANT 299 

and where the tower footings were mostly in loose shale. One 
U-bend of the river was crossed by means of a 2, 2 50-foot span be- 
tween the main supports, guided by an entirely unloaded tower at 
the bottom of the sag. 

Leaving the Piru Canyon, the line passes in an almost straight 
line across about 1 5 miles of rocky land covered with scattered oaks 
and chaparral. After reaching the last crest of this district, the 
line falls away rapidly to the open country surrounding Newhall. 
Across this entire district it was necessary to construct a permanent 
wagon road to haul supplies and permit of patrolling the line dur- 
ing operation. 

In the Newhall district, the line crosses the San Fernando 
Mountains directly west of the long tunnel on the Southern Pacific. 
Beyond this point it is in sight from the railroad track most of the 
way to Los Angeles, and throughout the greater portion of the route 
the line is erected in the open country, so that in case of necessity 
it can be repaired without excessive delay. 

Towers. — The transmission line is carried on galvanized steel 
towers, there being 1,140 of these towers. Their heights range 
from 30 feet to 60 feet. They are uniformly constructed of gal- 
vanized angle iron, bolted with galvanized bolts and held in shape 
by means of tension rods. There are no compressive braces ex- 
cept one pair in the upper portions of the sides and between the 
cross-arms. The nine insulators are spaced on 6-foot centres, five 
on the upper arm and four on the lower, the arms consisting of 9- 
inch 13^-pound channels. 

All portions of the tower are figured to be safe under a wind 
pressure of 30 pounds per square foot on the tower and the wire of 
a 700-foot span. The towers will also withstand absolute failure 
of any single wire, even though none of the resulting strain is trans- 
mitted to adjacent wires. 

Fig. 153 illustrates the construction of a standard 60-foot 
tower, which is 12 feet wide and 12 feet across at the base. The 
uprights are formed of 4-inch angles and the cross-braces of 21- 
inch, 3-inch, and 3J-inch angles, the diagonal rods being 11-16 



300 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

inch and § inch in diameter. Four insulators for the telephone 
lines are mounted on the third cross-bar, 21 feet above the ground. 
Forty of the towers were made extra heavy for use at points where 
the line changed its direction. 

The foot-plates of the towers are of cast iron, dipped in asphalt, 




Fig. 153. — Standard 6o-foot Steel Tower. 

and 24 inches in diameter. They are attached at the bottom to 
4X 4- inch foot posts, which are asphalted on top of the galvaniz- 
ing. These posts are bolted as extensions to the corner posts of 
the tower, and set in the ground a depth of 6 feet. Tapered holes 
were dug for these foot-plates and the earth was tamped back on 
them very carefully. No concrete footings were used, except on 



KERN RIVER PLANT 301 

some special work in the city of Los Angeles, where a great many 
of the tower heights exceeded 60 feet. The tower parts were made 
as light as was consistent with rigid construction. Under the ex- 
treme conditions mentioned above, the factor of safety in any steel 
member is specified to be not less than 2 J. 

No cast iron was permitted in the construction, except in the 
foot-plates. All connections are made with malleable-iron castings 
with a factor of safety of 4. The insulator pins are of cast steel 
and were furnished as a part of the tower. They are secured to 
the tower by four bolts and are cemented into the insulators. 

The towers were shipped from the factory knocked down, 
with their small parts boxed, and were hauled to their respective 
locations by wagon. They were assembled lying on the ground, 
and "kicked" into place by means of a gin pole. This method of 
erection was found to be very satisfactory for all sizes of towers, 
and only such towers as were located in rugged or inaccessible coun- 
try were built up piece by piece. 

In stringing out the wire, teams were used with usually four 
animals, although in limited spaces two horses on a tackle were 
substituted. Wherever possible, those wires which could be lifted 
onto the tower were strung out alongside and later on thrown into 
place. 

Line Construction. — The transmission line is designed to con- 
sist of three circuits with the wiring spaced symmetrically on 6-foot 
centres. This wire is seven-strand, 4-0 hard-drawn copper, hav- 
ing an elastic limit exceeding 35,000 pounds total, and an ultimate 
strength of 62,400 pounds. About 2,500,000 pounds of cable 
were used on the line. 

The wire was sampled and tested at the mill before being ac- 
cepted. It was greased and shipped on reels containing usually 
two 4,000-foot lengths. Some wire was also purchased in shorter 
lengths for convenient use in the mountain section. No special 
difficulty was, however, experienced in handling full-length pieces 
even in the most rugged country. 

The type of clamp used is shown in Fig. r 54. It is 2 inches long, 



302 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

and is constructed of three pieces, the inner piece being shaped to 
conform to the two wires. The tie wires passing around the neck 
of the insulator are of No. i copper strand. The four-bolt clamps 
are of brass, while the U-piece placed in the top of the insulator 
to prevent chafing is of No. 24 copper. The tie wires fail in test 
at about 4,000 pound. The clamps will withstand somewhat 




Fig. 154. — Double Insulator Showing Method of Tying. 

more, and the construction could readily have been made much 
stronger at a slight additional expense if it had been considered 
desirable. 

The insulators used are 18 inches in diameter, and the two lower 
petticoats are, respectively, 14 inches and 11 inches in diameter. 
Each assembled insulator weighs 50 pounds. The main contract, 
for 7,500 insulators, or over 90 per cent, of the total number, called 
for a glaze that would match the galvanized steel towers. The 
manufacturers were successful in producing an insulator with a light 
gray or slate-colored glaze which harmonizes very well with the hue 
of the towers. The resulting construction is comparatively in- 
conspicuous on the transmission line, and the insulators, being of 
this neutral shade, do not afford as prominent a target for mali- 
cious marksmen as do those of the ordinary brown glaze. 

The insulators were all carefully tested at the factory by one 
of the Edison Company's engineers. The specifications called 



KERN RIVER PLANT 



303 



for a guaranty of a 100,000- volt test from the groove to the pin for 
half an hour under a precipitation of 1 inch in five minutes at an 
angle of thirty degrees from the vertical. The assembled insulator 
was required to withstand under a wet test a potential of 150,000 




QL*- *) 

/ 

Fig. 155. — Section of Insulator. 

volts for 30 seconds, and the separate parts are guaranteed to with- 
stand a voltage of 25 per cent, in excess of the normal proportion 
of over-voltage test. 

The insulators are guaranteed to withstand a side strain of 
4,000 pounds and actually fail at approximately 9,000 pounds. The 
wire has an ultimate strength of 61,300, but its elastic limit, as 
noted above, will not much exceed 35,000. The normal failing 
point of the ties, 4,000 pounds, is, therefore, sufficiently high for 
safe construction, while they are not so strong as to stand more 
than the wire or the insulators. 

The transmission line, as stated elsewhere, is carried on spans 
as long as the character of the country would permit with towers 
not exceeding 60 feet in height. This maximum height was de- 
termined upon as being that which would give the lowest total 



304 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

cost of construction. The sags for the different spans being 
determined and the telephone clearances from transmission 
wires being assumed at a minimum of 7 feet, it was necessary 
to determine the tower spacings with minimum safe ground 
clearances in the different portions of the line. In order to do this 
accurately, survey parties were sent over the entire line, taking 
tower locations, and determining all elevations so that they were 
able to plot a profile of the transmission system showing the ele- 
vation of each tower, the height of the intermediate elevations and 
the important topography of the country. The parties designated 
the height of the tower while in the field, making their profile as 
they went along, and checking the resulting line before leaving that 
section of the country. 

A telephone circuit is carried the entire length of the trans- 
mission line, being supported on the towers about 20 feet above 
the ground. Between towers the wires are held up by wooden poles, 
two poles being necessary between towers for an average 700-foot 
span. 

Switching Stations. — The transmission lines are carried through 
from one end to the other, with transpositions only at switching 
stations. There are at present only three such buildings, at Tejon, 
Castaic, and San Fernando, the latter two of which contain trans- 
former substations. 

The switching station proper is equipped with two sets of oil- 
break switches for each line and two sets of knife-blade disconnect- 
ing switches for each line. The oil switches are connected, one 
set after another, into a complete circle. After passing through 
the disconnecting switches, the incoming lines are tapped between 
alternate oil switches. From the vacant jumpers left after these 
lines have been tapped in, their corresponding outgoing circuits are 
taken, and, after passing through the disconnecting switches, leave 
the building on the opposite side. 

The switching- station buildings are constructed of concrete in 
the most substantial manner. The circuits are isolated from 
each other bv means of concrete barriers and floors. Individual 



KERN RIVER PLANT 305 

leads of the same circuit are, however, run in the same compart- 
ment. In spite of the large number of crossings called for by the 
wiring diagram, the dimensions of the building are not excessive. 
The Castaic substation is 66 feet long and 41 feet 6 inches wide, 
with a cross-partition wall forming the switch-room. 4c feet wide, 
and the transformer-room 26 feet wide. Provision has been made 
to connect horn lightning arresters to the circuits at these sub- 
stations if it is found necessary after the line has been operated for 
some time. 

The two transformer substations have in their switching- 
houses an arrangement identical with that in the other stations, 
except that openings were made in the west wall, through which 
leads were taken into the adjacent transformer-house. The two 
were built together under the same roof and with continuous side 
walls so that there is on the exterior little to indicate the difference 
between the two ends of the station. In the transformer-house pro- 
vision has been made for two banks of 2,100-K.W. transformers 
from the transmission line at 60,000 volts and delivering to the dis- 
tribution at 30,000. The high-tension leads are tapped from two 
of the outgoing 60,000-volt circuits in the switching-house, and 
after passing through oil switches join in a common bus from which 
the transformers can be separated by means of knife-blade switches. 

This switch-gear, with the exception of the transformer switches, 
is on a concrete deck forming a complete second story in the switch- 
ing-house, 18 feet above the floor. On the under side of this floor 
there are also mounted the insulators for the 30,000-volt circuits. 
The 30,000-volt oil switches are, however, placed on top of the floor. 
The lightning arresters for the 60,000-volt circuits are on the wall 
between the transformer, and the switch-house, and are separated 
from each other by 6-foot barriers, while the 30,000-volt arresters 
are against the end of the substation immediately below the oil 
switches and the outgoing 30,000-volt circuits. 

At Castaic there will be installed at present one bank of trans- 
formers, 2-100 K.W., oil-filled and water-cooled. These trans- 
formers will supply power to a 30,000-volt, 40-mile transmission 

20 





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KERN RIVER PLANT 307 

system now being built by the Ventura County Power Company, 
west from Castaic to Saticoy, where a branch is taken off at Ox- 
nard, while the main line continues to Ventura. This branch will 
eventually be continued to Santa Barbara, 30 miles farther, where 
the Edison Electric Company has extensive power and railway 
holdings. 

At San Fernando is a 1,200-K.W. bank, which will supply 
power at 2,300 volts to lamps and motors. 

Los Angeles Receiving Station. — The Kern River No. 1 trans- 
mission line terminates in Los Angeles, 117 miles from the power 



Fig. 157. — Lines Entering Los Angeles Receiving Station. 

plant, at the steam and transformer station known as Los Angeles 
No. 3. This station is constructed to receive, transform, and dis- 
tribute to the local substations, power transmitted from the com- 
pany's water-power plants on Santa Ana River, Mill Creek, Lytle 
Creek, and Kern River, and also contains a large steam auxiliary 
plant to supplement the water-generated power. It receives power 
at 60,000 and 30,000 volts, and generates and distributes at 16,000 
and 2,300 volts. 

Both of the Kern River circuits enter the station through the 
east gable, as shown in Fig. 156. After passing through choke 
coils the lines enter oil switches which connect them to their re- 



308 DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

spective bus-bars. There is also an oil tie switch between the two 
buses. Each transformer has an oil switch which can be connected 
by means of a double-throw knife-blade switch to the bus-bars be- 
longing to the west or to the middle circuit. When the east circuit 
comes in, it will have a pair of oil switches so that it can be run on 
either of the bus-bars. 

There are four step-down 4,500-K.W. transformer banks, with 
their secondaries wound for either 16,000 or 32,000 volts. Under 
ordinary conditions, all energy received from Kern River will be 
handled through the double 15,000-volt bus. The transformers 
are cooled by forced-oil circulation. The oil, after leaving the 
transformer, is handled in the same manner as at Kern River. 
It enters a receiver, is forced by variable-speed centrifugal pumps 
into boiler-tube cooling coils outside the building, and passes back 
into the pressure line which fills the transformers. There being 
no extensive supply of cold water available, the cooling water is 
circulated continuously from the oil cooler basin into elevated 
troughs, from which it drops over a series of screens, where it is 
cooled immediately before falling on the section containing the 
hot oil. 

This building also contains provision for switching the old 
30,000- volt, 80-mile transmission line, fed by the Santa Ana and 
Mill Creek plants, with its various branches and all the 15,000 
volt distribution around Los Angeles. The arrangement of the 
various circuit bus-bars, oil switches, and the transformers is shown 
in the accompanying diagram. All switches and circuits are con- 
trolled from a 12 -panel switchboard on the gallery of the turbine- 
room, which is equipped with the necessary control switches and 
instruments for the 60,000-, 30,000-, 15,000-, and 2,300-volt buses. 

All bus-bar wiring connections to the transformers and the 
outgoing circuits are carried in ducts. In the new portion of the 
station these are filled with 15,000-volt leaded paper cables of 211,- 
ooo-cm. cross-section, with the exception of those for the turbo- 
generator, which has 400,000-cm. cables. 

There were installed in the steam end of this plant during 



KERN RIVER PLANT 



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3IO DEVELOPMENT AND DISTRIBUTION OF WATER POWER 

1903 two 2,000-K.W. 2,300-volt turbo- alternators, with 4,000 H.P. 
of water-tube boilers, in 500-H.P. units. When it became nec- 
essary to order an extension for the plant, in 1905, larger- size ap- 
paratus was determined upon throughout. An additional 5,250 
H.P. in 750-H.P. units was installed in the boiler-room. 

The turbine installation in the new plant consists of a single 
6,000-K.W. turbo-alternator, with condensing equipment. This 
unit is four-stage, single-flow, and is operated at from 27j-inchto 
28-inch vacuum. Thus far loads up to 10,000 K.W. have been 
carried on the machine without any indication of its maximum 
load being approached. 

The generator is wound for 16,500 volts, star connected, and 
is run with grounded neutral on the 50- cycle distribution of the 
company. The generator operates perfectly and runs in mul- 
tiple with the main system without causing any disturbance what- 
ever. Between the neutral of the machine and the station ground 
wire, a potential difference of several hundred volts exists under 
operating conditions, with the machine in connection with star-to- 
delta-connected transformer banks. This voltage and the re- 
sultant flow where the neutral switches close, vary with the number 
of transformers and the load on them, but does not appear to vary 
from other causes. An observation of the wave shape across the 
neutral connection showed a somewhat peaked potential wave at 
three times the frequency of the main circuit. For the present, the 
exchange current is limited by the insertion of the choke coil in the 
neutral connection. At a later date a resistance will be substi- 
tuted for the coil. This phenomenon in one shape or another 
is observable on all Y- connected four-wire generator installations. 

A transformer bank stepping from 15,000 to 2,200 volts is 
connected to the machine leads so that the auxiliaries can be 
transferred to the generator leads after the unit is in full operation. 



INDEX 



Alternating -current dynamos, 76 
Alternating currents, 71-73 

3-phase, 73 
Alternations of dynamos, 80 
Aluminum conductors, 114, 182 
Ammeters, 148 

connections of, 148 
Ampere, 71 
Animas Power and Water Co., hydraulic 

development of, 176 
Appendix: Computation of pressures 

set up in long pipes, 152 
Arches under power-houses, 39, 40 
Armature windings, 76, 79 

insulation of, 158 
Arrangement of wires, 115, 175, 190,258 
Arresters, lightning. See Lightning 

arresters. 
Automatic speed governors, 68 
Auxiliary steam plants, 2, 13, 215, 262, 

263 

Barbed wer.es for lightning protection, 

i35> 140 
Basins, settling, 49, 50 
Basis of computing power, 2 
Bearings, thrust, 63, 222 

water-cooled, 181, 291 
Belt-driven units, 75 
Bevel gearing, 63 
Booms, 166, 222, 231 
Bulkhead, 44 

Bus-bars, 91, 150, 192, 308 
By-pass valves, 180, 198 

Cables, underground, 191, 192, 259, 

260 
Canals and flumes, 32 
Centre of gravity, 16 
Chain hoist, 49 
Choke coils, 136, 241, 250, 297, 308 

connections for, 136 
Chutes, ice. See Ice chutes. 

log. See Log chutes. 
Circuit breakers, 149, 150 

automatic, 146 



Circuits. See Conductors; Direct cur- 
rent; Transmission lines; Wires 
single-phase. See Single-phase sys- 
tems, 
three-phase. See Three-phase sys- 
tems. 
Circular mils, 100 
Computation of power, 2, 10 
Computation of pressures set up in long 

pipes, 152 
Concrete conduits, 274 
Concrete dams. See Dams, con- 
crete. 
Conductors : 

aluminum, 114, 182 

arrangement of, 115, 175, 190, 244, 

.258 
distance between, 119, 175, 182, 244, 

258, 299, 301 
exit from power-houses, 132, 297 
heat liberated on passage of current, 

. 8 7 

ice-coating on, 120 

length of spans of, 120, 160 

resistance of, 100 

sag in, 118 

standard, 100 

steel for long spans, 160 

supports for long spans, 16 

swinging of suspended, 131 

telephone, 162 

transposition of, 116, 162, 190, 246 

underground, 191, 192, 259, 260 
Conduits, concrete, 274 
Converters, rotary. See Rotary con- 
verters. 
Copper wire, 10 1. See also Wires. 

current-carrying capacity, of 103 

hard-drawn, 101, 190, 301 

investment in, 111 

variation in amount required with 
voltage, 103 
Core walls for earth dams, 27 
Cost of equipment, 163 
Couplings: 

clutch, 186 



3i 



3 I2 



INDEX 



Couplings, flexible, 187, 188 

insulated, 187-188. 
Cranes, travelling, 48, 169, 207, 214, 

233> 28 4 
Crib dams. See Dams, crib. 
Cross arms, 122, 246 

bracing for, 123, 246 

treatment of, 123 
Cross-section of streams, measurement 

of, 6 
Current: 

alternating. See Alternating cur- 
rents. 

continuous. See Direct current. 

direct. See Direct current. 

heating due to, 87 
Curve of rear face of dams, 29, 196, 

266 
Cyclopean masonry, 30, 265 
Cylinder gates, 53 

Dams, 5, 16 

of Animas Power and Water Co., 
177 

centre of gravity of cross-section of, 
16 

concrete, 30, 172, 183, 196, 209, 265 

crib, 28, 170, 177 

curve of rear face of, 29, 196, 266 

design of, to withstand maximum 
floods, 5, 195 

drain gates in, 31 

earth, 26, 170, 177 

foundations of, 25, 196, 290 

frame, 28 

gravity, 24, 30, 209 

of Great Falls plant, 195 

important factors in designing, 25 

of Kern River plant, 264 

of McCall Ferry plant, 216, 224 

masonry, 29, 218, 231 

middle third of, 23 

overturning forces on, 20, 23 

pressures against, 18 

spillway of, 25-196 

Taylor's Falls plant, 230 

timber, 27 

Trenton Falls plant, 209 

West Buxton (Me.), 165, 170 
Deflecting nozzles, 67, 68, 180 
Design of hydro-electric power stations, 

38 
Detectors, ground, 149 
Development, of Animas Power and 
Water Co. (Colorado), 176 

at Drammen (Norway), 183 

at McCall Ferry (Pa.), 215 



Development, of Southern Power Co., 
at Great Falls, 193 

at Taylor's Falls (Minn.), 230 

at Tofwehult (Sweden), 154 

at Trenton Falls (N. Y.), 208 

at West Buxton (Maine), 164 
Direct current, 81, 162, 174 

from transmission lines, 162, 174, 258 
Division of power among units, 76 
Draft chests, 58 

Draft tubes, 39, 44, 52, 56, 203, 205, 
220, 233 

depth submerged, 59 

proportions of, 59 

velocity of flow in, 59 
Drain gates, 31 

Drammen (Norway) development, 183 
Drop, inductive, 81 

line, 103, 106, 190 

reactance, 105 
table of, 105 
variation with frequency, 105 

voltage, 103 
Dynamos, 62 

alternating-current, 76 

Animas Power and Water Co. 's plant, 
181 

cost influenced by speed of, 74 

direct-connected unit, 74 
comparison of costs of, 74 

direct -current, 71 

at Drammen (Norway) plant, 188 

efficiency of, 74, 77, 83, 88, 106, 174, 
188, 237 

inductor, 76 

of Kern River (Cal.) plant, 292 

losses in, 83 

revolving field, 77 

size of, for given service, 74, 86 

speed regulation of, 85 

at Taylor's Falls (Minn.) plant, 235 

at Tofwehult (Sweden) plant, 157 

at Trenton Falls (N. Y.) plant, 213 

"umbrella" type, 262 

variation of voltage in, 84, 237 

vertical, 62, 213 
thrust of, 63 

voltage of, 91, 92 

at West Buxton (Maine) plant, 173 

Earth dams, 26, 170, 177 

Effective voltage, 107 

Efficiency of dynamos, 74, 77, 83, 88, 106 

of Pelton water-wheels, 67 

of turbines, 59 
Electrical equipment, 71 
Energy losses in dynamos, 88 



INDEX 



3 J 3 



Excitation, dynamo field, 85, 91 

variation in, between full load and 
no load, 91 
Exciters, 73, 89, 90, 141, 143, 146, 184, 
187, 213, 222, 238, 292 
connections of, 91 
current for lighting from, 74, 296 
methods of driving, 89 
size of, 90, 91, 292 
temperature, rise of, 91 
Exit of conductors from power-house, 
132, 297 

Fall, measurement of, 10 
Field excitation, 85 
Flashboards, 170, 209, 275 
Float for measuring stream -flow, 5, 7 
Floating ice, 49 

Floods, change in head due to, 60 
Floor area of power-houses, 48 
Floors of power-houses. See Power- 
stations, floors of. 
Flow of streams, 2, 194, 216 

average velocity of, 6 

measurement of, 2, 5, 6, 8, 9 

over weirs, table of, 9 

per square mile of drainage area, 194, 
216 

variation in, 1, 194 
Flumes, concrete, 273 

velocity of flow in, 270 

wood, 176, 271, 276 
Fly-wheels on turbines, 86 
Forebays, 36, 50, 218, 222, 231, 275 
Foundations of dams, 25, 166, 196, 
226 

of power-houses, 48, 166, 282, 283 
Frame dams. See Dams, frame. 
Frazil ice, 49, 50 
Frequency, 80, 147, 148, 149 

of dynamos, 80 
Fuses, 150 

Gates, head. See Head -gates. 

sluice. See Sluice-gates. 

of turbines, 53 
comparison of, 55 
Gearing, bevel, 63 
Generators. See Dynamos. 
Governors, water-wheel. See Speed 

regulation of water-wheels. 
Gravity, centres of, 16 

dams. See Dams, gravity- 
Great Falls plant of Southern Power 

Co., 193 
Ground connections, 140, 149, 310 
Ground detectors, 149 



Hard-drawn copper wire, ioi, 190, 

301 
Head gates, 197, 201, 220, 243, 267, 276, 
282 

motors for, 202, 243, 282 
Head, loss of, in pipes, 35, 152 

net, 35 

reduction in, due to floods, 60 

suitable for impulse turbines, 65 
for pressure turbines, 59 
Heat liberated in conductors, 87 

in dynamos, 87 
Height of power-houses, 48 
High -head turbines, 212 
Horse-power, 71 

computation of, 10, 12 
Hydraulic developments: (See also De- 
velopment.) 

comparison of methods, 12 

cost of, 157 
Hydraulic power, computation of, 2, 10 

storage of, 3 
Hydraulic thrust bearings, 63 



Ice, 49, 166, 178, 222 

anchor, 215 

chutes, 220 

coating on wires, 120 

floating, 49 

frazil, 49 

gorge, 166 

removal of, 49 

surface, 49 
Impulse turbines, 64 
Impulse wheels, 46 

limiting heads for, 65 
Induction motors, power factor of, 71, 86 
Inductive drop, 80 
Inductive voltages in circuits, 86 
Inductor dynamos, 76 
Insulation of armature coils, 158 

breakdown test of, 158 

deterioration of, where overheated, 
88 
Insulator pins, 124 

deterioration of, 125 

iron, 125, 249 

size of, 125 

treatment of, 125 
Insulators, 123, 247, 302 

cost of, 124 

method of holding tp iron pins, 125, 
126, 248 

porcelain vs. glass, 123 

special tension, 162 

strain, 248 



3H 



INDEX 



Insulators: 

suspension type, 126 
advantages of, 129 
methods of using, 127 
towers for, 129 
tests of, 124, 302 
Intermittent power, 1, 2 

Jet impulse wheels, 66 
speed of, 66 

Kern River plant, 263 
Kilo-volt amperes, 87 
Kilo-watt, 71, 87 

Leakage, 120 

Leaves, removal of, 49, 50 

Lightning, 135 

Lightning arresters, 133, 136, 158, 188, 

2 97 
and choke coil combined, 137 
choke coils for, 136, 241, 250, 297 
connections for, 136, 140, 242, 250 
distribution of, along lines, 139 
ground connections for, 140, 251 
horn type, 137, 138, 139, 188, 192, 

2 49> 3°5 

knurled cylinder type, 136 

location of, 136, 139, 192, 259, 305 

water-jet type, 139 
Lightning protection, 135, 139, 249, 259 

by barbed wire, 135, 140 
Lines: {See also Conductors; Trans- 
mission^ lines ; Wires.) 

apparent energy loss in, 103 

drop in, 102 

energy loss in, 103 

lightning protection for, 135, 138, 
139, 140, 188, 192, 242 

three-phase, 107 
Load, inductive, 84 

non-inductive, 84 

variation in, 85 
Log chutes, 166, 167, 169, 231 
Long pipes, pressures set up in, 152 
Losses in dynamos, 83 

in lines, 102, 103, 106 

in power, 10, 83, 106 

in water-wheels, 59, 62, 74 

McCall Ferry plant, 215 

Market for water-power, 4 

Masonry, cyclopean, 30 

Masonry dams, 29 

Maximum power obtainable from 

hydraulic developments, 3 
Measurement of streams, 2, 5, 6, 8, 10 



Middle third in computations of sta- 
bility of dams, 23 

Motors, alternating-current, 72 
induction. See Induction motors. 

Nozzles, deflecting, 67, 68, 180, 284 

needle, 67, 180, 284 

for Pelton wheels, 67 
Number of alternations of a dynamo, 80 

of poles in a dynamo, 80 

Open penstocks, 41, 42, 56, 57, 58 

Pelton water-wheels, 66, 181, 288 

effective head on, 67 

power of, 67 

speed of, 66, 288 
Penstocks, 55 

open, 41 

division walls of, 56 
superiority of, 42 

steel, 40 
Piers under power-houses, 39, 167, 169 
Piles, 48 

Pins, insulator. See Insulator pins. 
Pipes, 32, 178, 202, 210 

anchoring of, on inclines, 180 

cast iron, t>Z 

computation of size of, 34 

kinetic energy of water column in, 69, 

152 
loss of head in, 34, 35, 152 
pressures produced in, 36, 69, 152 
riveting of, 180 
stand. See Stand pipes. 

steel, S3> 2II > 2 79> 28 * 
cost of, 34 
tapered, 178, 203 

velocity of water in, 34 

warming to prevent freezing, 178 

wood stave, ^^, 211 
Pole lines, 122, 159, 175, 182, 190, 243 
Poles, cost of, 121 

dimensions of, 176, 244, 245 

distance between, 120, 190, 244 

height of, 121 

iron, 192 

kinds of, 121 

life of, 121 

line, 120 

number of, in a dynamo, 80 

proportions of, 122 

setting of, 122, 245 

and towers compared, 121 
Potential drop in transmission lines, 85 
Power, available, 1 

computation of, 2, 10 



INDEX 



315 



Power, division of, among units, 75 

electrical, 71 

horse-, 71 

in an electric circuit, 71 

intermittent, 1, 2 

market for, 4 

maximum obtainable, 2, 3 
Power factor, 71, 86, 91 

of arc lamps, 71 

definition of, 86 

of induction motors, 71 
Power-houses. See Power stations. 
Power stations, bulkhead of, 44 

floor area of, 48 

floors of, 169 

location of, 34, 44 

materials used in construction of, 47 

piers under, 39, 167, 169, 206 

roofs of, 48, 169, 207, 284 

storage, 3, 11, 12 

types of, 38 
Pressure turbines, 51, 57 
Pressures against dams, 18 

on turbine wheels, 57 

set up in pipes, 36, 69, 152 

to overturn dams, 20, 23 
Protection against trash. See Booms; 
Racks; Trash. 

against ice. See Ice. 

Quarter-turns, 58 

Racks, 36, 50, 168, 178, 196, 198, 200, 

218, 231, 265, 275, 276 
Reactance, 105 

Reactance drops, table of, 105 
Register gates, 54 
Regulation of dynamos, 84 
speed, 85 
voltage, 91 

of transmission line, 85 

of turbine speed, 57, 67, 180, 200 
Regulators, voltage, 85, 96 
Relief pipe, 178 
Relief valves, 68, 212 
Reservoirs, 11 

drop in level allowable, 11 
Resonance, 86, 135 
Revolving field dynamos, 77 
Rheostats, 91 
Roofs for power-houses, 48, 169, 207, 

284 
Rope-driven units, 75 
Rotary converters, 81, 83, 85, 258 

Sand, action of, on water-wheels, 49 
removal of, 49, 184 



Sand trap, 184 

Settling basins, 49, 50 

Shear legs, 49 

Shock from transformers, 93 

Single-phase systems, 103, 112 

Sluice gates, 169, 183, 184, 198, 208, 275 

Sluice ways, 166, 169, 231, 267 

Southern Power Co.'s Great Falls 

plant, 193 
Spans, length of, for wires, 120 
Speed control of water-wheels, 57, 67 

180, 206, 234, 290 
Speed governors, 68 
Speed regulation of dynamos, 85 
Speed of water-wheels, 52, 57, 60, 66 
Spillway of dams, 25, 35 
Spouting velocity, 52 
Standard wires, 100 
Stand pipes, 37, 178, 211 
Static charge, protection against, 158 
Static discharge, 93, 135, 240 
Steam plants, auxiliary. See Auxiliary 

steam plants. 
Steel towers. See Towers, steel. 
Stop logs, 35 
Storage, hydraulic, 3, 11 

amount of, 11 
Stream flow, average velocity of, 6 

computation of, 194, 216 

equalization of, 3 

influence of forest growths on, 6 

measurement of, 4, 8 
Streams, cross-section of, 6 

effect of forest growths on flow of, 1 

flow of, 1, 2, 194, 216 

measurement of, 2 
Substations, 191, 253, 259, 304, 307 
Surface ice, 49 

Surging on transmission lines, 135 
Switchboards, 141, 143, 150, 189, 213 

connections of, 49, 257 

cost of, 92 

gallery for, 49, 284 

general rules in design of, 151 

iron framework for, 143, 144 

location of, 49 

panels of, 143 

wall braces for, 150 

at Drammen, Norway, 189 

Kern River plant, California, 295 

Taylor's Falls (Minn.), 242, 254 

Trenton Falls (New York), 213 

West Buxton (Maine), 174 
Switches, automatic, 14T, 174, 241 

chambers for, 141, 295 

generator field, 142 

high-tension, 49, 141, 144, 149, 305 



316 



INDEX 



Switches, oil, 141, 174, 189, 240, 241, 
294, 295, 305 

knife, 142 

three-phase, 142 
Switching and controlling apparatus, 

141, 239 
Synchronous machinery, 85 

speed of, relative to dynamo speed, 85 
Synchroscope, 146, 149 
Systems, comparison of Y and A con- 
nections, 99 

Delta-connected, 97 

resultant mesh-connected, 98 

star-connected, 97 

voltage of. See Voltage of systems. 

Table of cost of riveted steel pipe, 34 

of current allowable in bare copper 
wires, 103 

of dimensions and weights of bare 
copper wires, iot 

of flow over rectangular weirs, 9 

of reactance drop per 1000 feet of 
circuit, 105 

of resistances of bare copper wire, 101 

of thickness of core walls for earth 
dams, 27 

of weights of bare copper wire, 101 
Taylor's Falls — Minneapolis develop- 
ment, 230 
Telephone circuits on transmission 

pole lines, 162, 175, 190, 243, 300, 304 
Temperature rise in electrical apparatus, 

87, 88, 91 
Three-phase systems, 80, 107, 116, 148 

balancing of, 148 

computation of, 107, 113 

drop in, 107, in, 113 

effective voltage of, 108 

reactance of, 107 
Thrust bearings, 63, 222 
Thrust on turbine shafts, 61 
Timber dams, 27 
Towers, steel, 120, 246, 299 

cost of, 121 

spacing of, 303 
Transformers, advantages of large, 96 

air-cooled, 94, 213 

capacity of, 96 

cars and tracks for, 93, 190, 233, 239 

cases of grounded, 96 

chambers for, 93, 233, 238 

efficiency of, 96 

instrument, 147, 148, 149, 150 

location of, 73, 93 

methods of cooling, 94 

of connecting, 97, 293, 294 



Transformers, number required in 3- 
phase systems, 96 
oil-cooled, 93, 94, 237, 293, 308 
oil-insulated, 94, 95, 174, 293, 305 
overload on, 99 
regulation of, 96 
rollers under, 93, 190, 233, 254 
secondary of grounded, 97 
separate building for, 94, 208 
siphon for cooling, 95 
spare, 99 

step-down, 93, 106, 107 
step-up, 92, 106, 107 
water-cooled, 94, 174, 237, 254, 305 
Transmission conductors, 100. See also 
Conductors; Wires 
electrical problems of, 100 
mechanical problems of, 100 
Transmission lines, 92, 146, 159, 175, 
182, 190, 213, 243, 297, 301 
drop in, 102 
energy loss in, 103 
exit of, from power-house, 132 
inductive drop in, 81 
leakage on, 120 

poles for, 120. See also Poles; Pole 
lines. 
Transmission systems, Animas Power 
and Water Co. (Col.), 176 
Drammen (Norway), 183 
Great Falls (S. C), 193 
McCall Ferry (Pa)., 215 
Taylor's Falls (Minn.), 229 
three-phase. See Three-phase Sys- 
tems. 
Tofwehult-Westerwik (Sweden), 157 
Trenton Falls (N. Y.), 203 
voltage of. See Voltage of systems. 
Transposition of circuits, 116, 162, 190, 

246 
Trash, protection against, 35, 49, 167 
Trash racks. See Racks. 
Trees and shrubbery, effect of, on 

stream flow, 3 
Trenton Falls plant, 208 
Turbines, 51, 59 

arrangements of, to compensate for 

variations in head on, 60 
belt-connected, 46 

comparison of impulse and pressure 
types, 65 
of central draft chest and double 

draught-tube units, 58 
of costs of single and double units, 

direct-connected, 40 
division of power between, 57 



INDEX 



317 



Turbines, double units, 74 

drainage valves in case of, 203 
efficiency of, 59, 62, 74, 157, 187, 204, 

205 
fly-wheels on, 86, 186, 187 

gates of, 53 
high -head, 212, 213 
horizontal, 52, 55 
impulse, 64 
inward -flow, 51 

location of, 39, 40, 43, 44, 46, 52 
low-speed, 46 
methods of setting, 55 
outward-flow, 5 1 
parallel-flow, 51 
power of, 74 
pressures in, 57 
set in open penstocks, 41 
shell-encased, 40 
size of, 106, in, 204 
of Southern Power Co.'s Great Falls 

plant, 203 
speed of, 52, 60 

speed of gate opening allowable, 69 
speed regulation of, 57, 68, 69, 180 

186, 187, 234 
tandem-coupled, 46, 222 
of Trenton Falls plant, 213 
variation in head on, 60 
vertical, 52, 55, 62, 63, 213, 222 
Turns, quarter, 58 

Underground cables, 191, 192, 259, 

260 
Units, belt-driven, 75 

comparison of costs of, 74 

direct-connected, 74 

efficiency of, 74 

number of, for a given output, 75 

rope-driven, 75 

Value of a water-power, 4 
Valves, by -pass, 180 

relief, 68 
Variation in stream flow, 1 
Vegetable growths, effect of, 2 
Velocity of flow in draught tubes, 59 

in feed pipes, 34 

in flumes, 270 
Velocity of streams, 6 



Velocity, spouting, 52 

Volt, 71 

Voltage drop in lines, 85, 103 

regulators, 85, 96 
Voltage, of dynamos, 91, 92 

effective, in three-phase systems, 108 
of systems, 73, 80, 92, 93, 159, 162, 
163, 174, 175, 181, 184, 188, 190 
191, 213, 233, 237, 239, 243, 253, 
264, 293, 305, 307 
Voltmeters, connections of, 147 

Water-jets, protection against erosion 

of, 46 
Water-hammer, prevention of, 36 
Water-power, value of, 4 
Water-wheels, 51 

capacity of, 74 

governors for. See Water-wheels, 
speed regulation of 

height above tail water of, 47, 282 

impulse, 46 

location of, 39, 40, 43, 44, 46, 47 

speed regulation of, 57, 68, 180, 206, 
234, 288, 290 
Wattmeters, 148 
Watts, 71, 87 
Weirs, 8 

table of flow over, 9 
Wicket gates, 53 
Wires, aluminum, 114, 162 

arrangement of, 115, 175, 190, 244, 
258 

barbed, for lightning protection, 135, 
140 

distance apart of, 119, 175, 183, 244, 

2 5 8 > 2 99> 3°i 
exit of, from power-houses, 132, 297 
hard-drawn copper, 101 
ice-coating on, 120 
length of spans of, 120, 160, 303 
required for transmission, 73 
sag in, 118 
standard, table of dimensions, weights, 

and resistances, 100 
steel, for long spans, 160 
swinging of suspended, 131 
telephone, 162, 175, 190, 243, 258 
transposition of, 116, 162, 190, 246 
underground, 191, 192, 259, 260 



MAR 30 1908 



